Microfluidic device and method for its manufacture

Abstract

A fluidic, in particular microfluidic, device (10) is described, comprising at least two carrier plates (12, 14) arranged on top of each other made of Liquid Silicon Rubber (LSR), wherein at least one of the carrier plates (12, 14) has a fluidic structure (1, 5), characterized in that the carrier plates (12, 14) have a projecting, laterally circumferential outer contour (3a, 3b) which is positively overmolded with a second camera plastic component (9), so that the device (10) is media-tight.

Description

[0001] The present invention relates to a fluidic, in particular microfluidic, device and to a method for producing the same according to the preamble of the independent patent claims. State of the art

[0002] Transparent microfluidic chips with integrated channel structures and optical evaluation areas, for example for cell culture cultivation, are currently manufactured from transparent thermoplastics that are joined together using adhesive or welding processes, for example, with ultrasound or vibration. Fluidic devices made of non-stick and injection-moldable silicones are not currently manufactured because they cannot be joined using welding or adhesive methods.

[0003] DE 102016226194 A1 discloses an approach to produce a microfluidic chip using a liquid silicone rubber (LSR) material as an intermediate layer between a carrier plate and a cover plate.

[0004] DE 102010041287 A1 proposes to mold a cover element onto a cleaned or pretreated carrier plate or to form it with a stamp in order to produce a microfluidic chip. Disclosure of the invention

[0005] In contrast, the invention provides a fluidic, in particular microfluidic, device with at least two carrier plates arranged on top of one another, as well as a method for producing the same with the characterizing features of the independent patent claims.

[0006] Microfluidic devices are currently often manufactured from transparent thermoplastics that are joined together using adhesive or welding processes, for example. Welding processes generate particles and abrasion from the plastic, which can penetrate the channel structure. The use of adhesives for joining generates outgassing, which can affect cell cultures and the optical quality. Because cell cultures adhere strongly to thermoplastics, the surfaces of the microfluidic device that come into contact with the cell cultures must then be treated in an additional process step by specialized coating companies. In addition to the cost and logistical effort, this creates additional sources of error.

[0007] In contrast, the invention provides a fluidic, in particular microfluidic, device comprising at least two superimposed carrier plates made of liquid silicone rubber (LSR). The LSR is, for example, a transparent Silpuran® from Wacker or an Ultra Clear Silopren® from Momentive.

[0008] At least one of the carrier plates has a fluidic structure, in particular a microfluidic structure. The carrier plates each have a protruding, laterally circumferential outer contour, which is overmolded with a second plastic component in a form-fitting manner, making the device media-tight.

[0009] This provides a media-tight fluidic, particularly microfluidic, device with high transparency for optical evaluation and low adhesion of biological cells to the surfaces of the plastic fluidic channels. The molded transparent fluidic structures made of injection-moldable liquid silicone rubber (LSR) have a non-stick surface and, thanks to the irreversible crosslinking of the material, are highly temperature-resistant, for example, for sterilization.

[0010] Additionally, the material of the fluidic device is allergen-free, dermatologically acceptable, and biocompatible. This means there are no off-gassing emissions that could negatively impact cell cultures.

[0011] Further advantageous embodiments of the present invention are the subject of the subclaims.

[0012] In an advantageous embodiment, the second carrier plate has a flat surface. This makes the second carrier plate particularly simple and cost-effective to manufacture and easy to connect to a first carrier plate.

[0013] In a particularly advantageous embodiment, the first and second carrier plates have a very low surface roughness Rz of less than 0.1 µm. This is achieved, for example, by the mold inserts of the injection mold (see process steps a) and b) described later) having a surface roughness Rz of less than 0.1 µm. The cavities of the mold inserts are manufactured with this surface roughness, for example, using an ultra-precision machining process. The advantage of a surface roughness of 0.1µm for the first and second carrier plates is that they are very transparent, which is advantageous for later optical analysis. At the same time, the surfaces are very flat and smooth, especially in combination with the material's natural non-stick properties. The resulting seal between two plates is familiar from two glass plates that lie on top of each other and cannot simply be pulled apart.

[0014] Furthermore, it is advantageous if the second plastic component comprises a polycarbonate (PC), a cycloolefin polymer (COC), a cycloolefin copolymer (COP), an acrylonitrile-butadiene-styrene copolymer (ABS), a polymethyl methacrylate (PMMA), a styrene-acrylonitrile copolymer (SAN), and / or a polyolefin, in particular a polypropylene (PP) or a polyethylene (PE). Such plastics are advantageous because they are Food and Drug Administration approved, dimensionally and heat-resistant, and more cost-effective than LSR.

[0015] In a further advantageous embodiment, the second plastic component is reinforced or filled with glass fibers and / or minerals in order to improve the flatness and mechanical stability of the microfluidic device in a media-tight frame.

[0016] The second plastic component is, for example, the polyolefin Polyfort® from Lyondell Basell with a filler content of between 40% and 70%.

[0017] According to a further advantageous embodiment, the second plastic component has a surface roughness Rz of greater than 1 µm. This is achieved, for example, by the cavity of the assembly injection mold having a surface roughness Rz of greater than 1 µm in the process step d) described below. The advantage of a second plastic component with a surface roughness Rz of greater than 1µm is that the plastic frames do not have to be transparent and thus such a surface roughness is sufficient.

[0018] Another subject of the present invention is a method for producing a fluidic, in particular microfluidic, device. For this purpose, an injection molding machine with an LSR injection mold, interchangeable inserts, and an assembly injection mold are used. The method comprises the following steps: a) Molding a first carrier plate made of LSR with a fluidic structure and a protruding, laterally circumferential outer contour in a first mold insert of an injection mold b) molding a second carrier plate made of LSR with a protruding, laterally circumferential outer contour in a, in particular second, mold insert of an injection mold c) Arranging the first and second carrier plates on top of each other in an assembly injection mold d) Moving towards a parting plane of the assembly injection moulding tool, whereby the first and the second carrier plate are pressed against each other so that only the laterally circumferential outer contours are exposed in a cavity of the assembly injection moulding tool. e) Form-fitting overmolding of the outer contours along the sides with a second plastic component. For this purpose, the second plastic component is preferably injected via the sprue of the injection molding machine.

[0019] Using the method according to the invention, a fluidic, particularly microfluidic, device made of plastic with high transparency and low adhesion of biological cells in the fluidic channels can be manufactured using an injection molding process in a short production time and at low cost. The two overmolded LSR carrier plates optimally seal each other, both through the overmold and through their elastic behavior – it is a sealing material – so that no fluid can escape from the fluidic channels. Using the method according to the invention, the disadvantages of a welded or adhesive connection between the two carrier plates are eliminated, thus preventing the generation of particles, abrasion, or outgassing, which could have a negative impact on cell cultures.Thus, only a few process and assembly steps with a low number of error sources are necessary, making the component transparent, non-stick, media-tight and very cost-effective. Short description of the drawing

[0020] Advantageous embodiments of the present invention are illustrated in the drawing and explained in more detail in the following description. It shows: Fig. 1a: a schematic sectional view and top view of a first carrier plate with microfluidic structures of the device according to the invention in a first embodiment of the present invention, Fig. 1b: a schematic sectional view and top view of a first carrier plate with microfluidic structures of the device according to the invention according to a second embodiment of the present invention, Fig. 2a: a schematic sectional view and plan view of a second support plate of the device according to the invention with a flat surface according to a first embodiment of the present invention, Fig. 2b: a schematic sectional view and plan view of a second support plate of the device according to the invention with a flat surface according to a second embodiment of the present invention, Fig. 3: a schematic sectional view of a process step in the assembly injection mold for producing the fluidic device according to the invention according to the first embodiment of the present invention, Fig. 4a: a schematic representation of a device according to the invention according to a first embodiment of the present invention, and Fig. 4b: a schematic representation of an inventive device according to a second embodiment of the present invention. Embodiments of the invention

[0021] The same reference symbols refer to the same components. In Fig. Figure 1a shows a sectional view at the top and a plan view at the bottom of a first embodiment of a first carrier plate 12 made of LSR. The first carrier plate 12 advantageously has a surface roughness Rz of less than 0.1 µm. Furthermore, the first carrier plate 12 has fluidic, in particular microfluidic, structures 1, 5. Examples of these are shown in Fig. 1a shows eight ports 1 and four microfluidic channels 5. A fluid can be introduced into and discharged from the microfluidic channels 5 via the ports 1. Furthermore, the first carrier plate 12 has a protruding, laterally circumferential outer contour 3a. This is attached to the side surfaces of the first carrier plate 12 at the bottom, so that it is flush with the underside of the first carrier plate 12. Furthermore, the first carrier plate 12 has an optical reading window 8 for optical evaluation.

[0022] In Fig. 1b shows a sectional view at the top and a plan view at the bottom of a first carrier plate 12 made of LSR in a second embodiment. In contrast to Fig. 1a, the protruding, laterally circumferential outer contour 3a is arranged centrally on the side surfaces of the first carrier plate 12.

[0023] Fig. 2a shows a sectional view at the top and a plan view at the bottom of a second carrier plate 14 made of LSR in a first embodiment. The second carrier plate 14 advantageously has a surface roughness Rz of less than 0.1 µm. Furthermore, the second carrier plate 14 has a protruding, laterally circumferential outer contour 3b. This is attached to the side surfaces of the second carrier plate 14 at the bottom, so that it is flush with the underside of the second carrier plate 14. The underside of the second carrier plate 14 is designed as a flat surface 15.

[0024] Fig. Figure 2b shows a sectional view at the top and a plan view at the bottom of a second carrier plate 14 made of LSR in a second embodiment. In contrast to Fig. 2a, the protruding, laterally circumferential outer contour 3b is arranged centrally on the side surfaces of the second support plate 14. The underside of the second support plate 14 is designed as a flat surface 15.

[0025] In Fig. 3 shows the process step d) of the method according to the invention. The first 12 and the second carrier plate 14 - as shown in the Fig. 1a and Fig. 2a - are arranged one above the other in an assembly injection molding tool 20, so that the protruding, laterally circumferential outer contours 3a, 3b also rest on one another. The parting plane 25 of the assembly injection molding tool 20 is closed, so that the first 12 and the second carrier plate 14 are pressed against one another and only the laterally circumferential outer contours 3a, 3b are exposed in a cavity 23 of the assembly injection molding tool 20. The mold inserts of the assembly injection molding tool 20 forming the cavity 23 have, for example, a surface roughness of 1 µm. The injection cylinder 21 of the assembly injection molding tool 20 is filled with a second plastic component 9, in particular a reinforced one.In a further process step, not shown, the second plastic component 9 is injected via the sprue 22 into the cavity 23 of the assembly injection molding tool 20 so that it fills the latter and encloses the laterally circumferential outer contours 3a, 3b of the first 12 and the second carrier plate 13 and thus seals the fluidic device in a media-tight manner.

[0026] In Fig. 4a shows the fluidic, in particular microfluidic, device 10 according to a first embodiment of the present invention. The first projecting, laterally circumferential outer contour 3a of the first carrier plate 12 according to Fig. 1a and the second projecting, laterally circumferential outer contour 3b of the second carrier plate 14 according to Fig. 2a are arranged one above the other and enclosed by an overmolding 9 made of the solidified second plastic component 9, forming a media-tight fluidic device 10. The second plastic component has, for example, a surface roughness of 1 µm.

[0027] In Fig. 4b shows the fluidic, in particular microfluidic, device 10 according to a second embodiment of the present invention. The first projecting, laterally circumferential outer contour 3a of the first carrier plate 12 according to Fig. 1b and the second projecting, laterally circumferential outer contour 3b of the second carrier plate 14 according to Fig. 2b are enclosed by an overmolding 9 made of the solidified second plastic component 9, forming a media-tight fluidic device 10. The second plastic component has, for example, a surface roughness of 1 µm. The projecting laterally circumferential outer contours 3a, 3b of the first 12 and the second carrier plate 14 each project separately into the overmolding 9. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 102016226194 A1

[0003] DE 102010041287 A1

[0004]

Claims

[1] Fluidic, in particular microfluidic, device (10), comprising at least two carrier plates (12, 14) made of liquid silicon rubber (LSR) arranged on top of one another, wherein at least one of the carrier plates (12, 14) has a fluidic structure (1, 5), characterized by that the carrier plates (12, 14) have a protruding, laterally circumferential outer contour (3a, 3b) which is molded around with a second plastic component (9) in a form-fitting manner, so that the device (10) is media-tight. [2] Fluidic device (10) according to claim 1, characterized by that the second carrier plate (14) has a flat surface (15). [3] Fluidic device (10) according to one of the preceding claims, characterized by that the first (12) and the second carrier plate (14) have a surface roughness Rz of less than 0.1µm, so that the carrier plates (12, 14) are transparent and smooth. [4] Fluidic device (10) according to one of the preceding claims, characterized by that the second plastic component (9) comprises a polycarbonate (PC), a cyclo-olefin polymer (COC), a cyclo-olefin copolymer (COP), an acrylonitrile-butadiene-styrene copolymer (ABS), a polymethyl methacrylate (PMMA), a styrene-acrylonitrile copolymer (SAN) and / or a polyolefin, in particular a polypropylene (PP) or a polyethylene (PE). [5] Fluidic device (10) according to one of the preceding claims, characterized by that the second plastic component (9) is reinforced by means of glass fibers and / or minerals. [6] Fluidic device (10) according to one of the preceding claims, characterized by that the second plastic component (9) has a surface roughness Rz of greater than 1µm. [7] Method for producing a fluidic, in particular microfluidic, device (10) according to one of claims 1-4, comprising the following steps: a) molding a first carrier plate (12) made of liquid silicon rubber (LSR) with a fluidic structure (1, 5) and a protruding, laterally circumferential outer contour (3a) in a mold insert of an injection mold b) molding a second carrier plate (14) made of LSR with a protruding, laterally circumferential outer contour (3b) in a mold insert of an injection mold c) Arranging the first (12) and the second carrier plate (14) one on top of the other in an assembly injection molding tool (20) d) moving towards a parting plane (25) of the assembly injection moulding tool (20), wherein the first (12) and the second carrier plate (14) are pressed against one another, so that only the laterally circumferential outer contours (3a, 3b) are exposed in a cavity (23) of the assembly injection moulding tool (20). e) Form-fitting overmolding of the laterally circumferential outer contours (3a, 3b) with a second plastic component (9)

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