Microfluidic devices for capillary-driven fluid connections

Abstract

The present concept relates to a microfluidic device (1) for capillary-driven fluid connections between capillary channels (8, 16). The microfluidic device (1) comprises a first microfluidic system (4) comprising a first surface (5) and a first capillary channel (8), the first capillary channel (8) having an extension in a first plane, the first surface comprising an outlet opening (9) in a plane different from the first plane, the outlet opening defining an outlet area (35) in the first surface and adapted to allow fluid communication with the first capillary channel, thereby forming an outlet (12) of the first capillary channel; and a second microfluidic system (6) comprising a second surface (7) and a second capillary channel (16), the second capillary channel (16) having an extension in a second plane parallel to the first plane, and a portion of the second surface (7) comprising an inlet opening in a plane different from the second plane. and a second microfluidic system (6) having a capillary flow channel (8) and a second capillary flow channel (16) with an inlet opening (13) defining an inlet area (33) on the second surface and adapted to enable fluid communication with the second capillary flow channel, thereby forming an inlet (20) of the second capillary flow channel, wherein the first microfluidic system (4) and the second microfluidic system (6) are arranged with their first and second surfaces in contact such that the outlet (12) and the inlet (20) are coupled, thereby enabling a capillary-driven fluid connection between the first capillary flow channel (8) and the second capillary flow channel (16), and wherein the outlet area (35) overlaps at least a portion of the inlet area (33), and at least a portion of the inlet area (33) overlapped with the outlet area (35) is smaller than the outlet area (35).

Description

[Technical Field]

[0001] The present concept relates to a microfluidic device for capillary-driven fluid connections between capillary channels. [Background technology]

[0002] Connections between different capillary-driven fluidic components are often problematic and result in undesired arrest of capillary-driven flow, particularly at the risk of fluid flow being arrested at the interface between two capillary-driven fluidic components.

[0003] For example, reliable connection between a silicon microfluidic chip and a cartridge holding the chip without undesired cessation of capillary flow is an issue.

[0004] Therefore, there is a need for an apparatus that provides a reliable connection or interface between capillary-driven microfluidic systems, and in particular between silicon microfluidic chips and cartridges, that does not suffer from the problems associated with the prior art. Summary of the Invention

[0005] One object of the inventive concept is to solve at least one problem associated with the prior art. A particular object of the inventive concept is to solve a problem associated with providing a device having fluid connections between capillary channels of different microfluidic systems.

[0006] According to a first aspect of the inventive concept, there is provided a microfluidic device for capillary-driven fluid connections between capillary channels, the microfluidic device comprising: A first microfluidic system comprising a first surface and a first capillary channel, the first capillary channel has an extension in the first plane; a first microfluidic system, wherein the first surface comprises an outlet opening in a plane different from the first plane, the outlet opening defining an outlet area in the first surface and adapted to allow fluid communication with the first capillary channel, thereby forming an outlet for the first capillary channel; a second microfluidic system comprising a second surface and a second capillary channel; the second capillary channel has an extension in a second plane parallel to the first plane; a second microfluidic system, wherein a portion of the second surface comprises an inlet opening in a plane different from the second plane, the inlet opening defining an inlet area in the second surface and adapted to allow fluid communication with the second capillary channel, thereby forming an inlet for the second capillary channel; wherein the first and second microfluidic systems (6) are arranged with their first and second surfaces in contact such that the outlet and the inlet are coupled, thereby enabling a capillary-driven fluid connection between the first and second capillary channels; The exit area overlaps at least a portion of the entrance area, and at least the portion of the entrance area overlapping the exit area is smaller than the exit area.

[0007] According to a second aspect of the inventive concept, there is provided a method for manufacturing a second microfluidic system for coupling to a first microfluidic system (4) comprising a first surface (5) and a first capillary channel (8), the first capillary channel (8) having an extension in a first plane, the first surface comprising an outlet opening (9) in a plane different from the first plane, the outlet opening defining an outlet area (35) in the first surface and adapted to allow fluid communication with the first capillary channel, thereby forming an outlet (12) of the first capillary channel, the second microfluidic system comprising a second surface having an inlet opening and the second capillary channel in communication with the inlet opening, the second microfluidic system further comprising a stack of layers comprising a first layer and a second layer and a spacer layer between the first layer and the second layer, the method comprising: fabricating a spacer layer by laser cutting elongated cutouts in the spacer material, the elongated cutouts defining capillary channels of a microfluidic system; stacking a spacer layer to the second layer, and optionally one or more additional layers between the spacer layer and the second layer; cutting a hole with a short pulse laser through the second layer, and optionally through one or more additional layers, to the elongated cutout in the spacer layer, thereby communicating the inlet opening with the capillary channel; disposing a first layer on the spacer layer; Equipped with.

[0008] According to a third aspect of the inventive concept there is provided a device comprising a microfluidic device according to the first aspect for medical or diagnostic applications.

[0009] The above, as well as additional objects, features, and advantages of the inventive concept will be better understood through the following illustrative and non-limiting detailed description, taken in conjunction with the accompanying drawings, in which like reference numerals will be used for like elements unless otherwise specified. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a cross-sectional view of a microfluidic device. [Figure 2] FIG. 1 is a schematic diagram of a cross-sectional view of a microfluidic device. [Figure 3] (a) to (h) are schematic diagrams of the entrance and exit areas and overlapping areas. [Figure 4(a)] 1 illustrates overlapping entrance and exit areas. [Figure 4(b)] 1 illustrates overlapping entrance and exit areas. [Figure 4(c)] 1 illustrates overlapping entrance and exit areas. [Figure 5] FIG. 1 is a schematic diagram of overlapping entrance and exit areas. [Figure 6] FIG. 1 is a schematic diagram of a cross-sectional view of a microfluidic device. [Figure 7] Schematic diagrams of a microfluidic device comprising a stack of layers (a) and (b). [Figure 8] FIG. 1 is a schematic diagram of a cross-sectional view of a microfluidic device comprising a pore member. [Figure 9] Schematic diagrams of a microfluidic device comprising a stack of layers (a) and (b). [Figure 10] 1 is a schematic diagram of a method according to the concept of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] In view of the above, it would be desirable to provide an apparatus for capillary-driven fluid connection between a first microfluidic system and a second microfluidic system that is not impaired by the problems associated with the prior art. One object of the inventive concept is to address this problem and provide a solution to at least one problem or need associated with the prior art. Further and alternative objects can be seen from the following.

[0012] Any disclosure herein relating to one inventive aspect of the inventive concept may generally further relate to one or more of the other aspect(s) of the inventive concept.

[0013] It will be appreciated that the concept of the present invention is based, at least in part, on the unexpected discovery that connection problems can be solved or reduced by coupling two microfluidic systems via an interface where the outlet area overlaps at least a portion of the inlet area, and where at least a portion of the overlapped inlet area is smaller than the outlet area. Further unexpected discoveries include that this can be achieved by the outlet being larger than the inlet, in which case the outlet can completely overlap the inlet, or the outlet and inlet can be the same size, or the inlet can even be larger than the outlet, in which case the overlap is arranged such that the overlapped area is smaller than the outlet area. Unexpectedly, it has been found that such overlapping provides benefits including, for example, improved fluidic properties, without blocking capillary flow between the microfluidic systems.

[0014] According to a first aspect of the inventive concept, A microfluidic device for capillary-driven fluid connections between capillary channels is provided, the microfluidic device comprising: A first microfluidic system comprising a first surface and a first capillary channel, the first capillary channel has an extension in the first plane; a first microfluidic system, wherein the first surface comprises an outlet opening in a plane different from the first plane, the outlet opening defining an outlet area in the first surface and adapted to allow fluid communication with the first capillary channel, thereby forming an outlet for the first capillary channel; a second microfluidic system comprising a second surface and a second capillary channel; the second capillary channel has an extension in a second plane parallel to the first plane; a second microfluidic system, wherein a portion of the second surface comprises an inlet opening in a plane different from the second plane, the inlet opening defining an inlet area in the second surface and adapted to allow fluid communication with the second capillary channel, thereby forming an inlet for the second capillary channel; wherein the first and second microfluidic systems (6) are arranged with their first and second surfaces in contact such that the outlet and the inlet are coupled, thereby enabling a capillary-driven fluid connection between the first and second capillary channels; The exit area overlaps at least a portion of the entrance area, and at least the portion of the entrance area overlapping the exit area is smaller than the exit area.

[0015] An apparatus comprising a first microfluidic system comprising a first surface and a first capillary flow channel, the first capillary flow channel having an extension in a first plane, the first surface comprising an outlet opening in a plane different from the first plane, the outlet opening defining an outlet area in the first surface and adapted to enable fluid communication with the first capillary flow channel, thereby forming an outlet for the first capillary flow channel, the apparatus enabling capillary-driven flow of liquid through and out of the first microfluidic system.

[0016] An apparatus comprising a second microfluidic system comprising a second surface and a second capillary channel, the second capillary channel having an extension in a second plane parallel to the first plane, a portion of the second surface comprising an inlet opening in a plane different from the second plane, the inlet opening defining an inlet area in the second surface and adapted to enable fluid communication with the second capillary channel, thereby forming an inlet for the second capillary channel, the apparatus enabling capillary-driven flow of liquid into the second microfluidic system.

[0017] A first microfluidic system and a second microfluidic system, with the first surface and the second surface being arranged in contact such that the outlet and the inlet are coupled, enable the provision of a capillary-driven fluid connection between the first capillary flow channel and the second capillary flow channel, thereby enabling the flow of liquid between the microfluidic systems.

[0018] The first and second microfluidic systems each having a first surface and a second surface allow for efficient coupling of the microfluidic systems, for example, by contacting at least a portion of the first surface with at least a portion of the second surface.

[0019] The outlet area overlapping at least a portion of the inlet area provides fluid communication between the first capillary flow path and the second capillary flow path. Having at least a portion of the inlet area overlapping the outlet area smaller than the outlet area provides capillary-driven flow between the first capillary flow path and the second capillary flow path. Unexpectedly, it has been found that the inventive concept, including defining an inlet area overlapping an outlet area, allows for efficient, undisturbed flow, even capillary-driven flow, between the first and second flow paths compared to, for example, a larger overlapping area.

[0020] The second capillary channel may further comprise a second outlet positioned to expel liquid from the second capillary channel, thereby enabling liquid flow out of the second microfluidic system.

[0021] Placing the first and second surfaces in contact so that the outlet and inlet are coupled can be achieved in several suitable ways. The surfaces can be firmly pressed together, such as by clamping the first and second microfluidic systems with the first and second surfaces facing each other, with the outlet and inlet openings appropriately aligned or positioned. A layer with sealing properties, for example, a layer of flexible or compressible material, can be positioned between the first and second microfluidic systems. A layer or another material, such as an adhesive or sealing liquid, can be used between the first and second surfaces. Thus, for example, even if an adhesive is provided between the first and second surfaces, the first and second surfaces can still be considered to be in contact according to the present disclosure. The contact can be direct or indirect.

[0022] It is to be understood that the inlet opening and outlet opening defining the inlet area and outlet area, respectively, may be considered to be the area of ​​the first surface or second surface defined by the circumference of the inlet opening or outlet opening, respectively.

[0023] The second capillary channel may further comprise a second outlet arranged to expel liquid from the second capillary channel, whereby a flow of liquid out of the second microfluidic system may be enabled accordingly.

[0024] Having an overlapping entrance area smaller than the exit area can be achieved, for example, by the entrance area being smaller than the exit area, in which case the entire entrance area can overlap the exit area. The entrance area can, for example, be larger than the exit area or can be the same area, in which case the exit and entrance can be positioned relative to each other such that the exit overlaps only a portion of the entrance area, and the overlapped area is smaller than the exit area.

[0025] From this, the entrance area may have a smaller cross-sectional area than the exit area, thereby effectively realizing a method that allows the exit area to overlap at least a portion of the entrance area, where at least the portion of the entrance area that overlaps the exit area is smaller than the exit area.

[0026] The inlet area may have a cross-sectional area equal to or greater than the outlet area and may be arranged such that at least a portion of the overlapping inlet area is smaller than the outlet area, thereby providing an efficient capillary-driven fluid connection between the first and second capillary flow paths, and such an arrangement may benefit, for example, from a reduced risk of blockage of capillary-driven flow by contaminants, such as particles or sediments, that may be present in the liquid flowing from the outlet to the inlet and onward.

[0027] The outlet opening may be adapted to allow fluid communication with the first capillary flow path through the outlet passage and may preferably have an extension perpendicular to the extension of the first capillary flow path, thereby providing efficient fluid communication between the first capillary flow path and the outlet opening and further to the second capillary flow path.

[0028] The inlet opening may be adapted to allow fluid communication with the second capillary flow path through the inlet passage and may preferably have an extension perpendicular to the extension of the second capillary flow path, thereby providing efficient fluid communication between the second capillary flow path and the inlet opening and further to the first capillary flow path.

[0029] The outlet passage may have a cross-sectional area perpendicular to the main flow direction of the outlet passage that is the same or similar in size as the outlet area. The outlet area may be defined by an opening of the outlet passage in the first surface.

[0030] The inlet passage may have a cross-sectional area perpendicular to the main flow direction of the inlet passage that is the same or similar in size as the inlet area. The inlet area may be defined by the mouth of the inlet passage at the second surface.

[0031] The outlet opening may have a cross-sectional area corresponding to the outlet region of the first capillary flow channel, and the inlet opening may have a cross-sectional area corresponding to the inlet region of the second capillary flow channel, thereby enabling passive fluid flow between the capillary flow channels and the inlet / outlet with reduced risk of fluid interruption.

[0032] Thus, the first capillary flow path may have an outlet region and / or the second capillary flow path may have an inlet region. The outlet area defined by the outlet opening may correspond to the outlet region of the first capillary flow path. The inlet area defined by the inlet opening may correspond to the inlet region of the first capillary flow path.

[0033] The outlet passage may have a cross-sectional area corresponding to the outlet area of ​​the first capillary passage, and / or the inlet passage may have a cross-sectional area corresponding to the inlet area of ​​the second capillary passage.

[0034] An outlet / inlet opening or passage having a cross-sectional area corresponding to the outlet / inlet region of a first / second capillary channel can be described as an opening or cross-sectional protrusion on the wall of the first / second capillary channel having a similar or corresponding shape and / or size to the outlet / inlet region. Furthermore, according to embodiments, the width of the outlet / inlet opening can be similar to, the same as, or smaller than the corresponding or parallel width of the first / second capillary channel. In other words, an inlet or outlet opening according to embodiments can be described by essentially not extending outside the inlet / outlet region of the corresponding capillary channel. In embodiments of this aspect of the invention, relatively large inlets / outlets can be used, resulting in an uninterrupted capillary-driven fluid connection for reasons including the overlap discussed above. Even when the inlets and outlets are not perfectly aligned or centered, it is still possible to provide an uninterrupted capillary-driven fluid connection with efficient mating of the inlets and outlets. Additionally, a fluid connection with relatively low resistance can be achieved using relatively large inlets / outlets.

[0035] Thus, the first capillary flow path may have an outlet region and / or the second capillary flow path may have an inlet region. By outlet region, we mean the portion of the first capillary flow path that is adjacent or closest to the outlet opening compared to other portions of the first capillary flow path. By inlet region, we mean the portion of the second capillary flow path that is adjacent or closest to the inlet opening compared to other portions of the second capillary flow path.

[0036] The first capillary flow path may have an outlet region with a different width compared to the main portion of the first capillary flow path. For example, the first capillary flow path may have a width that widens or tapers toward the outlet. According to another example, the first capillary flow path may have a circular-shaped outlet region with a diameter that may be larger than the width of the main portion of the first capillary flow path, as illustrated in FIG. 4(a). Similarly, the second capillary flow path may have an inlet region with a different width compared to the main portion of the second capillary flow path, as illustrated in FIG. 4(a).

[0037] The microfluidic device may be a passive microfluidic device. By passive microfluidic device is meant a device as described in accordance with the first aspect and configured to allow all fluid communication and flow within the device to be actuated by passive capillary forces or capillary pressure, without the need for, for example, pressure or electrokinetic pumping or the assistance thereof. Flow in a passive microfluidic system may be actuated solely by capillary forces.

[0038] The second microfluidic system may comprise a stack of layers comprising a first layer and a second layer and a spacer layer between the first and second layers, the second layer having a second surface and a through hole with an inlet opening and arranged to provide fluid communication between the inlet opening and the second capillary flow path, the spacer layer having an elongated cutout extending in a second plane and parallel to the spacer layer, the elongated cutout arranged to define, together with an adjacent layer of the stack of layers, the second capillary flow path.

[0039] With such a stack of layers, microfluidic systems can be efficiently fabricated.

[0040] Adjacent layers can be, for example, the first and second layers, or two layers selected from, for example, the first, second, third, fourth, or fifth layer, or other layers.

[0041] One or more of the adjacent layers, which may be the first layer and / or the second layer, may comprise or be made of PET, preferably PET with hydrophilic properties, and may be in the form of a foil or film. The hydrophilic properties allow capillary-driven flow to be achieved with hydrophilic or aqueous liquids. The adjacent layer may be made of a DS PSA, for example, in the form of a film or foil. The height or dimension of the capillary flow path may be effectively selected or predetermined by selecting the thickness of the film or foil.

[0042] The second microfluidic system may consist of a stack of layers.

[0043] In the case of a microfluidic device comprising a stack of layers, the second layer may further comprise a pore member arranged to extend into and occupy the outlet opening and to extend into and occupy at least a portion of the cutout in the spacer layer, the pore member comprising a through hole with the inlet opening.

[0044] The hole member, which is positioned to extend into and occupy the outlet opening and to extend into and occupy at least a portion of the cutout in the spacer layer, allows for efficient positioning of the through hole during manufacture of the device.

[0045] The through-hole can be an inlet passage that allows fluid communication between the inlet opening and the second capillary flow channel.

[0046] The second layer may be a layer produced by molding, whereby the dimensions of the through holes or inlet passages may be defined during the molding process.

[0047] When the microfluidic device comprises a stack of layers, it may further comprise a third layer of the stack of layers disposed between the second layer and the spacer layer, the third layer comprising through holes arranged to allow fluid communication between the second layer and the spacer layer.

[0048] Thus, for example, a second microfluidic system can be designed such that the second capillary channel is provided with properties imparted by the third layer, while the second surface is provided with other properties imparted by the second layer, e.g., properties having an effect on capillary flow in the capillary channel can be controlled and provided by the third layer, and properties having an effect on the interface between the first and second microfluidic systems can be controlled and provided by the second layer.

[0049] For example, in a stack of layers consisting of first, second, and third layers and a spacer layer, the adjacent layers are the third and first layers.

[0050] It is understood that any additional layers to the first layer, second layer, and intermediate layer positioned between the second layer and the spacer layer, such as a third layer, may have through holes that coincide with the through holes of the second layer by at least partially overlapping the through holes of the second layer, thereby enabling fluid communication between the first capillary path and the second capillary path.

[0051] The second layer may be an adhesive layer that provides adhesion between the first and second microfluidic systems and / or between the first and second outer surfaces.

[0052] The layers of the stack of layers may be disposed parallel to the second outer surface.

[0053] The first microfluidic system may comprise a stack of layers comprising a first layer and a second layer and a spacer layer between the first and second layers, the second layer having a first surface and a through hole with an outlet opening and arranged to provide fluid communication between the outlet opening and the first capillary flow path, the spacer layer having an elongated cutout extending in a first plane and parallel to the spacer layer, the elongated cutout arranged to define the first capillary flow path together with adjacent layers of the stack of layers.

[0054] Hence, one or both of the first and second microfluidic systems may comprise or be fabricated from a stack of layers.

[0055] When the microfluidic device comprises an outlet channel and / or an inlet channel, the walls of the outlet channel and / or the walls of the inlet channel may be rendered hydrophilic, thereby providing an effect on the wettability of the outlet and / or inlet.

[0056] The first microfluidic system and / or the second microfluidic system can be made from a material that provides or can be modified to provide hydrophilic properties. For example, the microfluidic system can be made from PET with a hydrophilic coating, such as a PET layer with a hydrophilic coating. The microfluidic system can also be made from a material that includes chemical groups that allow the material to be modified to have hydrophilic properties, such as by chemical reaction or absorption.

[0057] Capillary-driven flow of a liquid requires one or more contact surfaces that the liquid can wet. As used herein, hydrophilicity of a material or surface is intended to be interpreted as one or more properties that allow the material or surface to be wetted by an aqueous or hydrophilic liquid. From this, hydrophilicity provides an attractive force between the surface or material and the liquid. From this, hydrophilicity enables capillary-driven flow. For example, materials comprising or consisting of glass or silica are understood to have hydrophilicity for systems with capillary-driven flow of aqueous liquids. Furthermore, suitable polymers that have hydrophilic properties, either inherent in the polymer or due to modifications, including, for example, chemical modifications or coatings, are considered hydrophilic and may facilitate or enhance capillary-driven flow.

[0058] The walls of the outlet channel and / or the walls of the inlet channel may be at least partially coated or contacted with a hydrophilic enhancing agent, which may cause the walls to provide a greater attraction to aqueous solutions compared to uncoated walls, thereby promoting or enhancing capillary-driven flow.

[0059] A hydrophilicity enhancer, as used herein, may be understood as an agent that increases or enhances the hydrophilicity of a wall compared to a wall in the absence of the hydrophilicity enhancer.

[0060] The hydrophilic enhancer may be selected from the group consisting of SiO2, surfactants, polymers such as PEG and PMOXA.

[0061] Any suitable hydrophilicity enhancing agent may be used. In addition to being selected to provide an appropriate enhancement of hydrophilicity, it may also be selected to have suitable properties for providing a coating on the material of the inlet channel and to have little or no negative effect on compounds or samples present in the system.

[0062] The first and / or second microfluidic systems may be fabricated from silicon, glass, or polymers, or combinations thereof, thereby enabling microfabrication of microfluidic systems by known methods. Furthermore, capillary-driven flow may be achieved within the device.

[0063] At least one of the layers of the stack of layers may comprise a material having capillary force enhancing or hydrophilicity enhancing properties in the second or first capillary flow path, in particular the material may comprise or be coated with SiO2.

[0064] The first microfluidic system and / or the second microfluidic system may for example be structures comprising further capillary channels, reaction or reagent compartments, and / or means for connection to other systems.

[0065] The first and second outer surfaces being arranged so that the outlet and inlet are coupled may be, for example, by positioning the first and second outer surfaces facing each other so that the outlet and inlet openings at least partially overlap.

[0066] Microfluidic devices can be used for medical and / or diagnostic purposes, for example, in medical and / or diagnostic devices. Microfluidic devices can be used with complex sample matrices, such as biological matrices. Examples of fluids that can be actuated or flowed within the device can be blood samples, urine samples, biological samples, or other complex and / or biological samples or fluids.

[0067] The device can be particularly useful with complex sample matrices.

[0068] According to another aspect of the inventive concept, there is provided a method for manufacturing a second microfluidic system for coupling to a first microfluidic system (4) comprising a first surface (5) and a first capillary channel (8), the first capillary channel (8) having an extension in a first plane, the first surface comprising an outlet opening (9) in a plane different from the first plane, the outlet opening defining an outlet area (35) in the first surface and adapted to allow fluid communication with the first capillary channel, thereby forming an outlet (12) of the first capillary channel, the second microfluidic system comprising a second surface having an inlet opening and the second capillary channel in communication with the inlet opening, the second microfluidic system further comprising a stack of layers comprising a first layer and a second layer and a spacer layer between the first layer and the second layer, the method comprising: fabricating a spacer layer by laser cutting elongated cutouts in the spacer material, the elongated cutouts defining capillary channels of a microfluidic system; stacking a spacer layer to the second layer, and optionally one or more additional layers between the spacer layer and the second layer; cutting a hole with a short pulse laser through the second layer, and optionally through one or more additional layers, to the elongated cutout in the spacer layer, thereby communicating the inlet opening with the capillary channel; disposing a first layer on the spacer layer; Equipped with.

[0069] The short pulse laser can be a picosecond, femtosecond, or attosecond type laser. Such a laser provides the desired hole, e.g., a hole with well-defined, smooth edges. The short pulse laser can be a laser called an ultrashort pulse laser.

[0070] The first and / or second capillary flow passages may include a coating of SiO2, which may facilitate capillary-driven flow. Furthermore, the surfaces and capillary action of the first and / or second capillary flow passages may thereby mimic the surfaces and capillary action of silica structures.

[0071] Such a first microfluidic system may be suitably connected or coupled to a second microfluidic system according to the third aspect, for example as described with reference to the first aspect.

[0072] The through-holes in the second layer may have similar or identical dimensions and area as those of the inlet opening.

[0073] According to a third aspect of the inventive concept there is provided a device comprising a microfluidic device according to the first aspect for medical or diagnostic applications.

[0074] 1, a microfluidic device 1 for capillary-driven fluid connection between capillary channels 8 and 16 will now be discussed. The microfluidic device 1 comprises a first microfluidic system 4 comprising a first surface 5 and a first capillary channel 8, the first capillary channel 8 having an extension in a first plane, and the first surface 5 comprising an outlet opening 9 in a plane different from the first plane. The outlet opening 9 defines an outlet area on the first surface 5 and is adapted to allow fluid communication with the first capillary channel 8, thereby forming an outlet 12 for the first capillary channel 8; the second microfluidic system 6 comprises a second surface 7 and a second capillary channel 16, the second capillary channel 16 having an extension in a second plane parallel to the first plane, a portion of the second surface 7 comprising an inlet opening 13 in a plane different from the second plane, the inlet opening 13 defining an inlet area on the second surface 7 and allowing fluid communication with the second capillary channel 16. the first microfluidic system 4 and the second microfluidic system 6 are arranged with the first surface 5 and the second surface 7 in contact such that the outlet 12 and the inlet 20 are coupled, thereby enabling a capillary-driven fluid connection between the first capillary channel 8 and the second capillary channel 16, and the outlet area overlaps with at least a portion of the inlet area, and at least the portion of the inlet area overlaid with the outlet area is smaller than the outlet area.

[0075] The first and second planes may further be parallel to the first and / or second surfaces.

[0076] The outlet opening 9 adapted to allow fluid communication with the first capillary flow path may be through a passage communicating with the first capillary flow path 8. The inlet opening 13 adapted to allow fluid communication with the second capillary flow path 16 may be through a passage communicating with the second capillary flow path.

[0077] 1 illustrates the device 1 in which the first microfluidic system 4 and the second microfluidic system 6 each have one capillary channel. According to other embodiments, multiple channels may be provided on the first microfluidic system 4 and / or the second microfluidic system 6.

[0078] The dimensions of the capillary channels 8 and 16 are shown schematically. The dimensions of the first capillary channel 8 and the second capillary channel 16 can be selected to provide a desired capillary force, and the dimensions can be selected differently depending on, for example, the properties of the liquid and / or material and / or the wall properties of the first capillary channel 8 and the second capillary channel 16. The cross-sectional shapes of the first capillary channel 8 and / or the second capillary channel 16 can be individually selected from, for example, rectangular, square, or circular. One or more dimensions of the cross-sectional shape of the first capillary channel 8 and / or the second capillary channel 16, such as width or height, can be 1 micrometer or more, for example, 1 to 1000 micrometers. This can provide appropriate dimensions for the first and / or second channels. In addition to one or more dimensions, the first and / or second channels can have one or more additional dimensions that are greater than the one or more dimensions.

[0079] The coupling of the outlet 12 and the inlet 20 may be explained by the at least partial overlap of the outlet opening 9 and the inlet opening 13, thereby enabling a fluid connection between the first microfluidic system 4 and the second microfluidic system 6 and between the first capillary channel 8 and the second capillary channel 16.

[0080] The first outlet 12 and the second inlet 20 may be holes or openings through the walls of the first and second microfluidic systems 4 and 6 comprising the first and second surfaces 5 and 7 of the first and second microfluidic systems 4 and 6, respectively, which openings have mouths into the first and second capillary channels 8 and 16, respectively. Thereby, coupling may be achieved by arranging the walls in contact with each other and the holes or openings at least partially overlapping.

[0081] The second capillary channel 16 may further comprise an optional second outlet 22 arranged to discharge liquid from the second capillary channel 16. The second outlet 22 is shown in Figure 1 with a dashed line and a reference number in parentheses to illustrate that it is optional.

[0082] The entrance area overlapping the exit area may be smaller than the exit area, and the overlapping area may be 90% or less, 75% or less, or 50% or less of the exit area. The overlapping area may be greater than 10% of the exit area. For example, the overlapping area may be in the range of 90% to 10%, or 90% to 25% of the exit area.

[0083] According to one example, in this particular example, circular outlet and inlet shapes with diameters of 500 micrometers and 300 micrometers, respectively, were used. In the example, the entire inlet overlapped the outlet, whereby the overlapped area was 36% of the outlet area. Such overlap is an example that provided a desirable fluid connection between the capillary channels without undesirable stoppages in capillary flow.

[0084] The first microfluidic system 4 and / or the second microfluidic system 6 may be fabricated from a material that provides, or can be modified to provide, hydrophilic properties in areas or surfaces where capillary-driven flow is desired. For example, such areas or surfaces may comprise, or be modifiable to comprise, hydrophilic groups, such as SiO groups.

[0085] The microfluidic device 1 includes an outlet opening and an inlet opening. When using the microfluidic device 1 to move a liquid, the device may be advantageously used such that the liquid is actuated by capillary forces from the first capillary channel 8 to the second at least capillary channel 16, thereby taking advantage of the fact that the at least a portion of the inlet area overlapping the outlet area is smaller than the outlet area. While it may be possible to move liquid in the opposite direction, it may suffer from the drawbacks and lack the advantages of the inventive concept. Thus, while inlet and outlet, as used herein, are intended to refer to flow during normal intended use of the device proceeding in the outlet-to-inlet direction, it will be recognized that flow may be actuated in the opposite direction.

[0086] It will be appreciated that the microfluidic device 1 and the first and second microfluidic systems 4 and 6 may comprise additional microfluidic connections and interfaces in addition to the interface between the outlet 12 and the inlet 20. For example, in accordance with the discussion below with reference to FIG. 2, FIG. 2 illustrates a microfluidic device 1 according to an embodiment. The first surface 5 may further comprise a second inlet opening 59 in a plane different from the first plane. The second inlet opening 59 may define a second inlet area on the first surface 5 and be adapted to allow fluid communication with the first capillary channel 8, thereby forming a second inlet 62 for the first capillary channel 8. This second inlet 62 may be connected or coupled to a second outlet 63 from the second microfluidic system 6 or another additional microfluidic system. The interface between the second inlet and the second outlet may be characterized similarly to the interface and overlap between the outlet area and the inlet area discussed with reference to FIG. 1. Although not illustrated in FIG. 2, the second outlet 63 may be in fluid communication with a flow path, such as a third microfluidic flow path.

[0087] The first plane is the plane in which the first capillary channel 8 has an extension. The first plane may be parallel to the first surface 5. The second plane is the plane in which the second capillary channel 16 has an extension. The second plane may be parallel to the first and / or second surface.

[0088] The interface between the outlet 12 and the inlet 20 will now be discussed with reference to FIGS. 3(a)-(h). Only portions of the device 1, such as the device discussed with reference to FIG. 1, are illustrated in FIGS. 3(a)-(h) for improved clarity. Except for FIGS. 3(a) and 3(e), which illustrate the microfluidic systems 4 and 6 side-by-side, the portions of the device 1 are illustrated in top view, with the first microfluidic system 4 illustrated above the second microfluidic system 6. The first capillary channel 8 is illustrated in black, and the second capillary channel 16 is illustrated in white. While the outlet opening 9 and the inlet opening 13 are each illustrated as having a circular cross-sectional shape corresponding to the outlet area 35 and the inlet area 33, respectively, it will be understood and appreciated that these shapes are merely illustrative examples. The cross-sectional areas of the inlet and outlet openings, and the inlet and outlet areas 33 and 35, may further be independently selected from, for example, a square, a rectangle, a triangle, a polygon, an ellipse, or a star shape. Furthermore, the inlet and outlet being wider than the capillary channel is merely an example in the illustration; they may alternatively and independently be the same width or smaller. The inlet area 33 and outlet area 35 in Figures 3(a)-(d) are identical. In Figures 3(e)-(h), the inlet area 33 is larger than the outlet area 35, approximately two times larger in the illustrated example. Figures 3(b) and (f) illustrate comparative examples in which the overlapping area is 100% of the outlet area 35 and is therefore not smaller than the outlet area 35. Figure 3(c) illustrates an example of an embodiment in which the overlapping area is smaller than the outlet area 35. Figure 3(d) also illustrates an example of an embodiment in which the overlapping area is smaller than the outlet area 35, smaller than the overlapping area in Figure 3(c). Therefore, the overlapping area being smaller than the outlet area 35 can be achieved by the inlet area 33 being the same size as the outlet area 35. Surprisingly, it has been found that such overlapping areas provide an efficient fluid connection for capillary-driven flow, even for large inlet areas 33 .

[0089] 3(e)-(h) illustrate a device 1 in which the inlet area 33 is larger than the outlet area 35. Coupling a capillary flow path with such an inlet area 33 and outlet area 35 can be problematic, resulting in, for example, blockage of capillary-driven flow. A comparative example, illustrated in FIG. 3(f), in which the overlapped area is 100% of the outlet area, can suffer from problems with flow. FIGS. 3(g) and (h) illustrate an embodiment in which the overlapped area is smaller than the outlet area 35, which can unexpectedly provide an efficient fluid connection with maintained capillary-driven flow even when the inlet area 33 is larger than the outlet area 35. Such an embodiment in which the inlet area is larger than the outlet area can benefit from easier fabrication while still achieving an efficient capillary connection.

[0090] Referring now to FIGS. 4(a)-(c), embodiments will be discussed with reference to experiments conducted to illustrate the advantages of having at least a portion of the inlet area 33 overlapping the outlet area 35 be smaller than the outlet area 35. A portion 100 of the device 1, including the interface between the first outlet 12 and the second inlet 20, is depicted in FIGS. 4(a)-(c), illustrating the experimental setup. A portion of a first microfluidic system 4, including a first capillary channel 8 having an outlet opening 9 defining the outlet area 35, can be seen in FIG. 4(a). A white dotted circle 190 is depicted in FIG. 4(a) to highlight the outlet area 35. A portion of a second microfluidic system 6, including a second capillary channel 16 having an inlet opening 13 defining the inlet area 33, can also be seen in FIGS. 4(a)-(c). A white dotted circle 192 is depicted in FIG. 4(b) to highlight the inlet area 33. An experiment was conducted in which an exit area 35 overlaps a portion of an entrance area 33. The adjacent entrance area 33 with overlapping exit area 35 is highlighted in Figure 4(c) as the area surrounded by a jumble of white lines 194.

[0091] By adjusting the first microfluidic system 4 and the second microfluidic system 6 relative to each other, different overlaps were obtained and tested for fluidic connection. In the experiments, three parallel first and second microfluidic systems, referred to as System 1, System 2, and System 3 in Table 1, were used to increase the amount of experimental data generated. Experiments were judged based on successful fluidic connection, i.e., visually confirmed fluid transfer from the first capillary channel 8 through the outlet opening 9 to the inlet opening 13 and into the second capillary channel 16. Only passive liquid flow was used, i.e., driven by capillary forces. An aqueous buffer solution was used, referred to as lysis buffer in the experiments.

[0092] In particular, from Figures 4(a)-(c), the inlet opening 13 is larger than the outlet opening, which might be expected to make a passive fluid connection difficult, and initial experiments showed that perfectly aligned outlet and inlet, where the overlapping area is 100% of the outlet area, was not successful or could not be performed without problems.

[0093] In calculations based on experimental data, the area approximately represented by the white dotted circle or lines 190, 192, or 194 was calculated using software and used to calculate the overlap as a percentage of the exit area. The experimental and calculation results are provided in Table 1.

[0094] [Table 1]

[0095] Notably, all experiments were deemed successful and provided the desired fluid connection except when misalignment occurred, which could be considered 0% overlap, and further, except when the overlap was 100% of the outlet area. It can therefore be concluded that a fluid connection was successful as long as there was overlap of the inlet area, and as long as the overlap was up to 100% of the outlet area. The present invention therefore provides a reliable and efficient passive capillary-driven fluid connection, even when going from a smaller outlet to a larger inlet. Problems with the fluid connection are anticipated when going from a smaller outlet to a larger inlet. An unexpected discovery according to embodiments of the present invention can be based, at least in part, on the edges of the inlet / outlet or inlet / outlet channels, which promote capillary forces and create the effect of an inlet that behaves at least partially as if the inlet were a similar size to the outlet, and thus, at least to a lesser extent, in an environment where the flow front does not behave or appear to enter a wider channel.

[0096] In the example microfluidic device illustrated in Figures 4(a)-(c), the outlet channel has a cross-sectional area corresponding to the outlet region of the first capillary channel, and the inlet channel has a cross-sectional area corresponding to the inlet region of the second capillary channel. Furthermore, in this example, the inlet area corresponds to the inlet region, and the outlet area corresponds to the outlet region. In Figures 4(a)-4(c), the white dotted circle 190 may also be seen to indicate the outlet region, and the white dotted circle 190 may also be seen to indicate the inlet region of the illustrated device.

[0097] Variation in the area of ​​a single outlet between tests arises from the calculation of the area for each test, not from actual variation in the inlet or outlet.

[0098] 5 illustrates the inlet area 33 and outlet area 35 of device 1, depicted as dashed and solid rectangles, respectively, with a first microfluidic system 4 illustrated above a second microfluidic system 6. Other portions of device 1, such as capillary channels 8, 16, are not illustrated. The embodiment illustrated in FIG. 5 has an outlet area 35 that overlaps at least a portion of the inlet area 33, with at least the portion of the inlet area 33 overlapping the outlet area 35 being smaller than the outlet area 35. The inlet area 33 overlapping the outlet area 35 is illustrated with diagonal lines. Thus, one way to achieve the inlet area 33 overlapping the outlet area 35 being smaller than the outlet area 35 is by making the inlet area 33 smaller than the outlet area 35.

[0099] For example, as illustrated in FIG. 5, the at least a portion of the entrance area 33 may be 100% of the entrance area 33.

[0100] 3(c) and (d), the entrance area 33 and the exit area 35 may have the same size, and in addition, as illustrated in Figures 3(g) and (h), the exit area may be smaller than the entrance area, whereby a portion of the entrance area is overlapped such that at least a portion of the entrance area 33 with the overlapping exit area 35 is smaller than the exit area 35. From this, it should be appreciated that the entrance area 33 and the exit area 35 may be different sizes relative to each other, one larger than the other and vice versa, or may be the same size, and all or a portion of the entrance area 33 may be overlapped by the exit area 35, so long as the condition that at least a portion of the entrance area 33 with the overlapping exit area 35 is smaller than the exit area 35 is realized.

[0101] Referring now to FIG. 6 , a microfluidic device 1 according to a different embodiment of the device 1 will be described and illustrated in a cross-sectional view. In FIG. 6 , only a portion 100 of the device 1 is illustrated, including the interface between the first outlet 12 and the second inlet 20. In FIG. 6 , the inlet 20 has an inlet area 33, which in the illustrated example corresponds to the cross-sectional area of ​​the inlet 20 perpendicular to the flow direction 26 at the second inlet 20, and is overlapped by an outlet area 35. The inlet area 33 overlapped by the outlet area 35 is smaller than the outlet area 35, thereby enhancing the capillary forces that actuate the liquid into the second capillary channel 16. In FIG. 6 , the walls 24 of the outlet channel 19 and the outlet region 10 are at least partially coated with a hydrophilic enhancing agent 38, thereby providing an effect on the wettability of the first outlet 12. It is to be appreciated that liquid that is more efficiently driven through the first capillary flow channel 8 by capillary action may wet and fill the outlet region 10 and the first outlet 12 by contacting the hydrophilic enhancing agent 38, thereby forcing the liquid into contact with the second inlet 20 of the second capillary flow channel 16. In the illustrated example, further drive of the liquid by capillary action from the outlet 12 to the inlet 20 is further facilitated or enhanced by the outlet area 35 overlapping at least a portion of the inlet area 33, with at least the portion of the inlet area 33 with which the outlet area 35 is overlapped being smaller than the outlet area 35. A larger cross-sectional area of ​​one of the outlet 12 or the inlet 20 compared to the other may provide efficient overlap and coupling between the first outlet 12 and the second inlet 20. Having the inlet area 33 smaller than the outlet area 35 is one efficient way to achieve this overlapping area being smaller than the outlet area 35. Thereby, the capillary forces that actuate the liquid into the second capillary channel 16 may be enhanced by the provision of a narrower channel and increased wall surface area at the interface.

[0102] The outlet opening 9 may be adapted to allow fluid communication with the first capillary flow path 8 via an outlet passage 19, as illustrated, and the inlet opening 13 may be adapted to allow fluid communication with the second capillary flow path via an inlet passage 29, as illustrated. The inlet passage 29 may preferably have an extension perpendicular to the extension of the second capillary flow path, as illustrated. And the outlet passage may preferably have an extension perpendicular to the extension of the first capillary flow path, as illustrated.

[0103] Referring now to FIGS. 7(a) and 7(b), a microfluidic device 1 in which a second microfluidic system 6 comprises a stack of layers 102 will be discussed. Capillary flow in the microfluidic device 1 during one intended or typical use of the microfluidic device 1 is illustrated schematically by arrows in the capillary channels 16, 8. FIG. 7(a) illustrates components and details of the microfluidic device separated from one another and illustrated in a top view, while FIG. 7(b) illustrates a side view of the microfluidic device 1 comprising the components and details illustrated in FIG. 7(a). The stack of layers 102 comprises a first layer 104 and a second layer 106, and a spacer layer 108 between the first layer 104 and the second layer 106. The second layer 106 comprises a second surface 7 and a through-hole 110 comprising an inlet opening 13, positioned to provide fluid communication between the inlet opening 13 and the second capillary channel 16. The spacer layer 108 extends in a second plane and has elongated cutouts 112 parallel to the spacer layer, which are arranged to define, with adjacent layers of the stack of layers 102, the second capillary channel 16. The adjacent layers in the illustrated embodiment correspond to the first layer 104 and the second layer 106. It should be apparent from FIGS. 7( a) and 7(b) that the dimensions of the second capillary channel are determined or defined by the thickness of the elongated cutouts 112 and the intermediate layer 108, including the width w of the elongated cutouts 112, which defines the width of the second capillary channel, and the thickness of the intermediate layer 108, which defines the height h of the second capillary channel 16. In the illustrated example, w is 300 micrometers and h is 40 micrometers. A first microfluidic system 4 comprising a first capillary channel 8 is further illustrated in Figure 7(b) but not in Figure 7(a). The illustrated example demonstrates a first microfluidic system 4 comprising an outlet having an outlet area 35 that is the same size as the inlet area 33 but overlaps only a portion of the inlet area 33, the outlet area 35 being smaller than the inlet area 33. The first microfluidic system 4 and the second microfluidic system 6 are arranged with a first surface 5 and a second surface 7 in contact. Suitably (not illustrated), the first surface 5 and the second surface 7, and thereby the first microfluidic system 4 and the second microfluidic system 6, may be in contact, for example, by gluing or bonding.For example, the second layer 106 may be adhesive, such as by being made from an adhesive substrate tape. Such a tape may be, for example, a DS PSA substrate tape, suitably having a thickness of 10 to 100 micrometers, for example 40 micrometers.

[0104] 7(b) , the first microfluidic system 4 may comprise a stack of layers, regardless of whether the second microfluidic system 6 comprises the stack of layers 102, including a first layer and a second layer and a spacer layer between the first and second layers, the second layer having a first surface and a through-hole with an outlet opening, arranged to provide fluid communication between the outlet opening and the first capillary channel 8. The spacer layer of the stack of layers of the first microfluidic system 4 may have an elongated cutout extending in a first plane and parallel to the spacer layer, the elongated cutout arranged to define the first capillary channel 8 with an adjacent layer of the stack of layers.

[0105] A microfluidic device 1 comprising a stack of layers 102, in which a second layer 106 further comprises a pore member 120, will now be discussed with reference to FIG. 8 . Illustrated in FIG. 8 are a second microfluidic system 6 and a first microfluidic system 4, and a stack of layers 102 comprising a first layer 104 and a second layer 106, and a spacer layer 108 between the first and second layers. It will be appreciated that the first capillary channel 8 and the second capillary channel 16 are arranged similarly to the arrangement illustrated in FIG. 7 , but may be oriented differently, for example. The second layer 106 further comprises a pore member 120 arranged to extend into and occupy the outlet opening 9 and to extend into and occupy at least a portion of the cutout 112 in the spacer layer 108, the pore member 120 comprising a through-hole 110 comprising the inlet opening 13. The through-hole is illustrated using a white dashed line. 8 , the through-hole 110 provides fluid communication or a pathway between the first capillary flow path 8 and the second capillary flow path 16 by way of a mouth 122 to the second capillary flow path 16 facilitated by a cutout 122 in the pore member 120, the mouth or cutout 122 providing a flow path between the through-hole 110 and the second capillary flow path 16. The cutout 122 is illustrated by a gray dotted line. It is realized that in addition to the cutout 122, different suitable methods of providing the mouth 122 and fluid communication between the through-hole 110 and the second capillary flow path 16, such as a channel or hole, may be used. The illustrated pore member 120 is cylindrical in shape to suitably enable it to extend into and occupy the outlet opening 9, which in this example is circular in shape, and to be positioned to extend into and occupy at least a portion of the cutout 112 in the spacer layer 108. For example, if the outlet opening 9 is rectangular, the aperture member 120 may have a portion that extends into the outlet opening 9 and has a rectangular cross section.

[0106] By providing the perforated member 120 with a through hole 110 having an inlet opening 13, the outlet area 35 effectively overlaps with the inlet area 33, and the inlet area 33 overlapped with the outlet area 35 is smaller than the outlet area 35.

[0107] Coupling of the first and second microfluidic systems is easy with the pore member 120 extending into the outlet opening 9 .

[0108] The second layer 106 further comprises a pore member 120 and may suitably be manufactured integrally, preferably by a molding process. The second layer 106 further comprising a pore member may alternatively be manufactured from a material that may be provided with hydrophilic or capillary-driven flow promoting properties, such as by surface modification within the through-holes 110. As can be seen in Figure 8, the second surface may be essentially planar, but the pore member protrudes from the second surface 7.

[0109] 9(a) and (b), a microfluidic device 1 similar to the microfluidic device 1 discussed with reference to FIGS. 9(a) and (b) will now be discussed, except that it includes an additional third layer 109 in the layer stack 102 of the second microfluidic system 6. The layer stack 102 further includes the third layer 109 of the layer stack 102 disposed between the second layer 106 and the spacer layer 108, the third layer 109 including through-holes 111 arranged to allow fluid communication between the second layer 106 and the spacer layer 108. In such a configuration, the second layer 106 may be a bonding layer, such as made from an adhesive tape. In the illustrated example, in a layer stack 102 consisting of a first layer 104, a second layer 106, and a third layer 109, and a spacer layer 108, the adjacent layers are the third layer 109 and the first layer 104.

[0110] Suitably, in embodiments of the present inventive concept, the first microfluidic system 4 and / or the second microfluidic system 6 may be fabricated from silicon, glass, or polymer, or a combination thereof.

[0111] In the case of an embodiment comprising a stack of layers 102, at least one of the layers of the stack of layers 102 may comprise a material having capillary force enhancing properties in the second capillary flow path, in particular the material may comprise or be coated with SiO2.

[0112] 10, a method 200 for fabricating a microfluidic system, which may be, for example, a first microfluidic system 4 or a second microfluidic system 6, is discussed. The microfluidic system comprises a surface having an inlet opening and a capillary channel in communication with the inlet opening, the microfluidic system comprising a stack of layers comprising a first layer and a second layer and a spacer layer between the first and second layers, the method comprising: fabricating 202 a spacer layer by laser cutting elongated cutouts in the spacer material, the elongated cutouts defining capillary channels of the microfluidic system; Stacking 204 the spacer layer to the second layer, and optionally one or more additional layers between the spacer layer and the second layer; cutting 206 a hole with a short pulse laser through the second layer, and optionally through one or more additional layers, to the elongated cutout in the spacer layer, thereby communicating the inlet opening with the capillary channel; disposing 208 a first layer over the spacer layer; Equipped with.

[0113] The use of a short pulse laser provides improved hole properties, including smooth edges.

[0114] The short pulse laser can be, for example, a picosecond, femtosecond, or attosecond type laser.

[0115] The inventive concepts have been described above primarily with reference to a limited number of examples. However, as will be readily recognized by those skilled in the art, examples other than those disclosed above are equally possible within the scope of the inventive concepts as defined by the appended claims. The following is a summary of the claims as originally filed: [1] A microfluidic device (1) for capillary-driven fluidic connections between capillary channels (8, 16), said microfluidic device (1) comprising: A first microfluidic system (4) comprising a first surface (5) and a first capillary channel (8), the first capillary channel (8) has an extension in a first plane; a first microfluidic system (4), wherein the first surface comprises an outlet opening (9) in a plane different from the first plane, the outlet opening defining an outlet area (35) in the first surface and adapted to allow fluid communication with the first capillary channel, thereby forming an outlet (12) of the first capillary channel; A second microfluidic system (6) comprising a second surface (7) and a second capillary channel (16), the second capillary channel (16) has an extension in a second plane parallel to the first plane; a second microfluidic system (6), wherein a portion of said second surface (7) comprises an inlet opening (13) in a plane different from said second plane, said inlet opening defining an inlet area (33) in said second surface and adapted to allow fluid communication with said second capillary channel, thereby forming an inlet (20) of said second capillary channel; wherein the first microfluidic system (4) and the second microfluidic system (6) are arranged with the first surface and the second surface in contact such that the outlet (12) and the inlet (20) are coupled, thereby enabling a capillary-driven fluid connection between the first capillary channel (8) and the second capillary channel (16); A microfluidic device (1), wherein the outlet area (35) overlaps with at least a portion of the inlet area (33), and the at least a portion of the inlet area (33) overlapped with the outlet area (35) is smaller than the outlet area (35). [2] The microfluidic device (1) according to [1], wherein the inlet area (33) has a smaller cross-sectional area than the outlet area (35). [3] the outlet opening is adapted to allow fluid communication with the first capillary flow path via an outlet passage, preferably having an extension perpendicular to an extension of the first capillary flow path; the inlet opening is adapted to allow fluid communication with the second capillary flow channel via an inlet channel (29), and preferably has an extension perpendicular to the extension of the second capillary flow channel; The microfluidic device (1) according to [1] or [2]. [4] the outlet opening has a cross-sectional area corresponding to an outlet area of ​​the first capillary channel; the inlet opening has a cross-sectional area corresponding to an inlet area of ​​the second capillary channel. The microfluidic device (1) according to any one of [1] to [3]. [5] the second microfluidic system (6) comprises a stack of layers comprising a first layer (104) and a second layer (106) and a spacer layer (108) between the first layer (104) and the second layer (106); the second layer (106) comprises the second surface (7) and a through hole (110) comprising the inlet opening (13), and is arranged to provide fluid communication between the inlet opening (13) and the second capillary channel (16); The microfluidic device (1) according to any one of [1] to [4], wherein the spacer layer has an elongated cutout extending in the second plane and parallel to the spacer layer, the elongated cutout being arranged to define the second capillary channel (16) together with an adjacent layer of the stack of layers. [6] The microfluidic device (1) described in [5], wherein the second layer further comprises a pore member arranged to extend into and occupy the outlet opening and to extend into and occupy at least a portion of the cutout in the spacer layer, the pore member comprising the through hole comprising the inlet opening. [7] A microfluidic device (1) as described in [5] or [6], further comprising a third layer (109) of the stack of layers (102) arranged between the second layer and the spacer layer, the third layer having through holes arranged to enable fluid communication between the second layer and the spacer layer. [8] The first microfluidic system (4) comprises a stack of layers comprising a first layer and a second layer and a spacer layer between the first layer and the second layer; the second layer having the first surface and a through hole with the outlet opening, the second layer being positioned to provide fluid communication between the outlet opening and the first capillary channel; A microfluidic device (1) according to any one of [1] to [7], wherein the spacer layer has an elongated cutout extending in the first plane and parallel to the spacer layer, the elongated cutout being arranged to define the first capillary channel (8) together with an adjacent layer of the stack of layers. [9] A microfluidic device (1) according to any one of [3] to [8], wherein the walls of the outlet channel (24) and / or the walls of the inlet channel (29) are rendered hydrophilic, thereby providing an effect on the wettability of the outlet (12) and / or the inlet.

[10] The microfluidic device (1) described in [9], wherein the first microfluidic system (4) and / or the second microfluidic system (6) are manufactured from a material that provides or can be modified to provide the hydrophilicity.

[11] The microfluidic device (1) according to

[10] , wherein the wall (24) of the outlet channel and / or the wall (29) of the inlet channel are at least partially coated or contacted with a hydrophilic enhancing agent (38).

[12] The hydrophilic enhancer is SiO 2 , from a group consisting of surfactant, PEG, and PMOXA The microfluidic device (1) according to

[11] is selected.

[13] The microfluidic device (1) according to any one of [1] to

[12] , wherein the first microfluidic system (4) and / or the second microfluidic system (6) are manufactured from silicon, glass, or a polymer, or a combination thereof.

[14] At least one of the layers of the stack of layers comprises a material having capillary force enhancing properties in the second capillary channel, and in particular, the material is SiO 2 or The microfluidic device (1) according to any one of [5] to

[13] , which is coated with the above.

[15] A method (200) for manufacturing a second microfluidic system for coupling to a first microfluidic system (4) comprising a first surface (5) and a first capillary channel (8), the first capillary channel (8) having an extension in a first plane, the first surface comprising an outlet opening (9) in a plane different from the first plane, the outlet opening defining an outlet area (35) in the first surface and adapted to allow fluid communication with the first capillary channel, thereby forming an outlet (12) of the first capillary channel, the second microfluidic system comprising a second surface having an inlet opening and a second capillary channel in communication with the inlet opening, the second microfluidic system further comprising a stack of layers comprising a first layer and a second layer and a spacer layer between the first layer and the second layer, the method comprising: fabricating the spacer layer by laser cutting elongated cutouts in a spacer material (202), wherein the elongated cutouts define the capillary channels of the microfluidic system; Stacking (204) the spacer layer to the second layer, and optionally one or more additional layers between the spacer layer and the second layer; cutting (206) a hole with a short pulse laser through the second layer, and optionally through the one or more additional layers, to the elongated cutout in the spacer layer, thereby communicating the inlet opening with the capillary channel; disposing (208) a first layer on the spacer layer; A method comprising:

[16] A device for medical or diagnostic use, comprising the microfluidic device according to any one of [1] to

[14] .

Claims

1. A microfluidic device (1) for capillary-driven fluid connections between capillary channels (8, 16), said microfluidic device (1) comprising: A first microfluidic system (4) comprising a first surface (5) and a first capillary channel (8), the first capillary channel (8) has an extension in a first plane; a first microfluidic system (4), wherein the first surface comprises an outlet opening (9) in a plane different from the first plane, the outlet opening defining an outlet area (35) in the first surface and adapted to allow fluid communication with the first capillary channel, thereby forming an outlet (12) of the first capillary channel; A second microfluidic system (6) comprising a second surface (7) and a second capillary channel (16), the second capillary channel (16) has an extension in a second plane parallel to the first plane; a second microfluidic system (6), wherein a portion of said second surface (7) comprises an inlet opening (13) in a plane different from said second plane, said inlet opening defining an inlet area (33) in said second surface and adapted to allow fluid communication with said second capillary channel, thereby forming an inlet (20) of said second capillary channel; wherein the first microfluidic system (4) and the second microfluidic system (6) are arranged with the first surface and the second surface in contact such that the outlet (12) and the inlet (20) are coupled, thereby enabling a capillary-driven fluid connection between the first capillary channel (8) and the second capillary channel (16); the exit area (35) overlaps at least a portion of the entrance area (33), and the at least a portion of the entrance area (33) overlapped by the exit area (35) is smaller than the exit area (35); A microfluidic device (1), wherein the cross-sectional area of ​​the inlet area (33) is greater than the cross-sectional area of ​​the outlet area (35).

2. the outlet opening is adapted to allow fluid communication with the first capillary flow channel via an outlet passage, and preferably has an extension perpendicular to an extension of the first capillary flow channel; the inlet opening is adapted to allow fluid communication with the second capillary flow channel via an inlet channel (29), and preferably has an extension perpendicular to the extension of the second capillary flow channel; A microfluidic device (1) according to claim 1.

3. the outlet opening has a cross-sectional area corresponding to an outlet area of ​​the first capillary channel; the inlet opening has a cross-sectional area corresponding to an inlet area of ​​the second capillary channel. A microfluidic device (1) according to claim 1 or 2.

4. the second microfluidic system (6) comprises a stack of layers comprising a first layer (104) and a second layer (106) and a spacer layer (108) between the first layer (104) and the second layer (106); the second layer (106) comprises the second surface (7) and a through hole (110) comprising the inlet opening (13), and is arranged to provide fluid communication between the inlet opening (13) and the second capillary channel (16); 4. The microfluidic device (1) of claim 1, wherein the spacer layer has an elongated cutout extending in the second plane and parallel to the spacer layer, the elongated cutout being arranged to define, together with an adjacent layer of the stack of layers, the second capillary channel (16).

5. 5. The microfluidic device (1) of claim 4, further comprising a third layer (109) of the stack of layers (102) disposed between the second layer and the spacer layer, the third layer comprising through holes arranged to allow fluid communication between the second layer and the spacer layer.

6. the first microfluidic system (4) comprises a stack of layers comprising a first layer and a second layer and a spacer layer between the first layer and the second layer, the second layer having the first surface and a through hole with the outlet opening, the second layer being positioned to provide fluid communication between the outlet opening and the first capillary channel; 6. The microfluidic device (1) of claim 1, wherein the spacer layer has an elongated cutout extending in the first plane and parallel to the spacer layer, the elongated cutout being arranged to define, together with an adjacent layer of the stack of layers, the first capillary channel (8).

7. A microfluidic device (1) according to any one of claims 3 to 6 dependent on claim 2, wherein the walls of the outlet channel (24) and / or the walls of the inlet channel (29) are provided with hydrophilic properties, thereby providing an effect on the wettability of the outlet (12) and / or the inlet.

8. 8. The microfluidic device (1) according to claim 7, wherein the first microfluidic system (4) and / or the second microfluidic system (6) are manufactured from a material that provides or can be modified to provide said hydrophilic properties.

9. 9. The microfluidic device (1) according to claim 8, wherein the walls (24) of the outlet channel and / or the walls of the inlet channel (29) are at least partially coated or contacted with a hydrophilic enhancing agent (38).

10. The hydrophilic enhancer is SiO 2 10. The microfluidic device (1) according to claim 9, wherein the surfactant is selected from the group consisting of surfactants, PEG and PMOXA.

11. The microfluidic device (1) according to any one of claims 1 to 10, wherein the first microfluidic system (4) and / or the second microfluidic system (6) are made from silicon, glass or polymer, or a combination thereof.

12. At least one of the first and second layers comprises a material having capillary force strengthening properties in the second capillary flow path, and in particular, the material is SiO 2 7. A microfluidic device (1) according to claim 4 or 6, comprising or coated with:

13. A microfluidic device (1) as described in claim 5, wherein at least one of the first, second and third layers comprises a material having capillary force enhancing properties in the second capillary flow path, in particular the material comprises or is coated with SiO2.

14. A method (200) for manufacturing a second microfluidic system (4) comprising a first surface (5) and a first capillary channel (8), the first capillary channel (8) having an extension in a first plane, the first surface comprising an outlet opening (9) in a plane different from the first plane, the outlet opening defining an outlet area (35) in the first surface and adapted to allow fluid communication with the first capillary channel, thereby forming an outlet (12) of the first capillary channel, the second microfluidic system comprising an inlet a second surface having an inlet opening and a second capillary channel in communication with said inlet opening, said inlet opening defining an inlet area (33) in said second surface; the first microfluidic system (4) and the second microfluidic system (6) are arranged with the first surface and the second surface in contact such that the outlet (12) and the inlet (20) of the second capillary channel (16) are coupled, thereby enabling a capillary-driven fluid connection between the first capillary channel (8) and the second capillary channel (16); the exit area (35) overlaps at least a portion of the entrance area (33), and the at least a portion of the entrance area (33) overlapped by the exit area (35) is smaller than the exit area (35); the cross-sectional area of ​​the inlet area (33) is greater than the cross-sectional area of ​​the outlet area (35); The second microfluidic system further comprises a stack of layers comprising a first layer and a second layer and a spacer layer between the first layer and the second layer, and the method further comprises: fabricating 202 the spacer layer by laser cutting elongated cutouts in a spacer material, wherein the elongated cutouts define the first and second capillary channels of the first and second microfluidic systems; Stacking (204) the spacer layer to the second layer, and optionally one or more additional layers between the spacer layer and the second layer; cutting 206 a hole with a short pulse laser through the second layer, and optionally through the one or more additional layers, to the elongated cutout in the spacer layer, thereby communicating the inlet opening with the second capillary channel; disposing a first layer (208) on the spacer layer; A method comprising:

15. A device comprising a microfluidic device according to any one of claims 1 to 13 for medical or diagnostic applications.

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