阅读说明：本技术 用于制造3d微流体装置的方法 (Method for manufacturing 3D microfluidic devices ) 是由 弗洛里安·拉腊曼迪 蒂博·奥内热 于 2020-01-23 设计创作，主要内容包括：公开了用于产生3D微流体装置的方法,用于产生微流体装置(20)的方法(100),该方法包括产生主模具(1)的步骤(101)。主模具(1)包括第一支撑件(2)和第二支撑件(8),第二支撑件包括基片(3)和微结构(4)。该基片(3)具有第一表面和与第一表面相对的第二表面。产生主模具的步骤包括以下子步骤：-通过在基片(3)的第一表面上形成微结构(4)来产生(1011)第二支撑件(8)；-使用3D打印机,利用打印树脂,来3D打印(1012)第一支撑构件(2),第一支撑件(2)的尺寸与基片(3)的尺寸相适配,以便保持基片(3)；-将第二支撑件(8)的基片插入(1014)第一支撑件中。(A method for producing a 3D microfluidic device, a method (100) for producing a microfluidic device (20) comprising the step (101) of producing a master mould (1) is disclosed. The main mould (1) comprises a first support (2) and a second support (8) comprising a substrate (3) and a microstructure (4). The substrate (3) has a first surface and a second surface opposite to the first surface. The step of creating the master mould tool comprises the sub-steps of: -creating (1011) a second support (8) by forming a microstructure (4) on a first surface of a substrate (3); -3D printing (1012) the first support member (2) with a printing resin using a 3D printer, the dimensions of the first support member (2) being adapted to the dimensions of the substrate (3) in order to hold the substrate (3); -inserting (1014) the substrate of the second support (8) into the first support.)

1. A method (100) for manufacturing a microfluidic device (20), the method comprising the step of producing (101) a master mould (1), the master mould (1) comprising a first support (2) and a second support (8), the second support comprising a substrate (3) and a microstructure (4), the substrate (3) having a first face and a second face opposite to the first face, the step of producing the master mould comprising the sub-steps of:

-producing (1011) the second support (8) by forming a microstructure (4) on a first face of a substrate (3);

-performing three-dimensional printing (1012) of a first support (2) on a 3D printer using a printing resin, the dimensions of the first support (2) being adjusted according to the dimensions of the substrate (3) to accommodate the substrate (3);

-inserting (1014) the substrate of the second support (8) into the first support.

2. The method (100) according to claim 1, wherein the step of three-dimensional printing (1012) of the first support (2) comprises:

-before the step of inserting (1014) the substrate of the second support (8) into the first support (2), stopping (1013) the sub-step of printing of the first support (2) according to the height of the printed first support (2); and

-continuing the sub-step of printing (1015) the first support from the height of the first support (2), the microstructures (4) being aligned with the printed pattern of the first support (2), the continuing sub-step being carried out after the inserting step (1014).

3. The method (100) of claim 2, wherein:

-the first and second faces of the substrate (3) are separated by a substrate thickness (Es);

-stopping the printing of the first support (2) as soon as the total height (Htot), equal to the sum of the thickness (Ef) of the bottom of the printed first support (2) plus the thickness (Es) of the substrate of the second support (8), has a value greater than or equal to a predetermined threshold value;

-inserting the substrate of the second support (8) into the first support so that the second face of the substrate rests on the bottom of the first support;

the method further comprises the sub-steps of:

-cutting (1011bis) the substrate of the second support (8) around the microstructure (4) after the second support (8) is produced, the dimensions of the first support (2) being adjusted according to the dimensions of the cut substrate (3) to accommodate the cut substrate (3).

4. A method according to any one of claims 2 to 3, wherein the step of creating the master mould tool further comprises the sub-steps of:

-positioning (1011ter) a toolhead (5) of the 3D printer at a determined position before the printing step;

-removing (1013bis) the tool-holder of the 3D printer after the step of stopping printing and before the step of inserting;

-adding a resin (1014bis) on the first face of the base sheet of the second support (8) after the inserting step;

-positioning (1014ter) the tool holder in the determined position before continuing printing.

5. The method according to any one of claims 1 to 4, wherein, in the step (1011) of producing a second support (8), the forming of the microstructures comprises implementing one of the techniques comprising photolithography, wet or dry wafer engraving, 2-photon techniques, 3D printing with resolution comparable to photolithography.

6. The method (100) according to any one of the preceding claims, further comprising the step (102) of duplicating the master mould (1) to produce a first secondary mould (11) from the master mould and a second secondary mould (12) from the first secondary mould (11).

7. The method (100) of claim 6, wherein the microfluidic device (20) comprises at least one layer (17, 18), the method comprising:

-in a step (104) of producing the at least one layer (17, 18), a step of producing (103) an encapsulation mold (16) configured to fit with the second sub-mold (12); and

-a step (104) of production of at least one layer (17, 18), the step (103) of production of the encapsulation mold (16) comprising:

-a sub-step (1031) of 3D printing a packaging master mould;

-a substep (1032) of further duplicating the main encapsulation mold to produce a secondary encapsulation mold and producing said encapsulation mold (16) based on the secondary encapsulation mold.

8. The method (100) according to claim 7, wherein the generating of the at least one layer (104) comprises:

-a sub-step of moulding (1041) at least one layer by depositing moulding material between a second sub-mould (12) and an encapsulating mould (16), said encapsulating mould (16) and second sub-mould (12) being pressed against each other to ensure surface contact between an upper element of the second sub-mould (12) and a surface of the encapsulating mould (16);

-an annealing sub-step (1042) of the material between the second sub-mould (12) and the packaging mould, at a certain temperature for a determined period of time (16).

9. The method (100) according to any one of claims 7 or 8, wherein said at least one individual layer (17, 18) comprises at least two layers, which are superimposed and fixed to each other after being aligned with respect to each other, so as to form a three-dimensional microfluidic device.

10. The method (100) according to any one of claims 7 to 9, wherein it comprises a first step (101bis) of computer-aided design of the at least one layer (17, 18) according to the three-dimensional design of the microfluidic device (20), and a second step (101ter) of computer-aided design of the main mould (1) and of the encapsulating main mould according to the definition of the at least one layer (17, 18).

11. A master mold for fabricating a microfluidic device (20), the master mold comprising:

-a first support (2) produced by 3D printing; and

-a second support (8) comprising a substrate (3) and a microstructure (4), the substrate (3) having a first face and a second face opposite to the first face, the microstructure being formed on the first face of the substrate (3);

-the dimensions of the first support (2) are adjusted according to the dimensions of the substrate (3) to accommodate the substrate (3), the microstructures (4) being aligned with the printed pattern of the first support (2).

12. A flexible counter mold (11) for manufacturing a microfluidic device (20), said flexible counter mold (11) being a replica of the main mold according to claim 11 in a first material capable of being cross-linked, said first material being flexible after cross-linking.

13. A rigid counter-mold (12) for manufacturing a microfluidic device (20), said rigid counter-mold (12) being a replica of the flexible counter-mold (11) according to claim 12 in a second material capable of cross-linking, which second material is rigid after cross-linking.

14. A layer (17, 18) for manufacturing a microfluidic device (20), the layer (17, 18) being a replica of the rigid counter mould (11) according to claim 13 in a third material capable of cross-linking.

15. A microfluidic device (20), said microfluidic device (20) comprising at least two layers (17, 18) according to claim 14, said at least two layers (17, 18) being placed and fixed to each other, the pattern of one of the at least two layers being aligned with the pattern of another of the at least two layers to form nodes distributed in three dimensions and microchannels, said microchannels fluidly connecting said nodes.

Technical Field

The present invention relates to the field of microfluidic devices, and in particular to methods for manufacturing such devices.

Background

Microfluidic devices are used to replicate systems that manipulate small volumes of fluid by using channels of a few microns in size. For applications in biology, it is known to fabricate two-dimensional devices using the molding of Polydimethylsiloxane (PDMS) on a substrate on which micro-channels have been imprinted using photolithography. 3D printing can produce more complex three-dimensional devices, but the resolution of 3D printing is not sufficient to produce the desired microfluidic devices, and the materials used in 3D printing are not compatible with the conditions under which these devices are used for biological assays. On the other hand, existing methods for manufacturing these devices are not very time efficient and cannot accommodate mass production.

Disclosure of Invention

It is therefore an object of the present invention to provide a solution for all or part of these problems.

To this end, the invention relates to a method for manufacturing a microfluidic device, the method comprising a step of creating a master mould comprising a first support and a second support, the second support comprising a substrate and a microstructure, the substrate having a first face and a second face opposite to the first face, the step of creating the master mould comprising the sub-steps of:

-manufacturing a second support by forming microstructures on the first side of the substrate;

-three-dimensionally printing a first support on a 3D printer using a printing resin, the dimensions of the first support being adjusted according to the dimensions of the substrate to accommodate the substrate;

-inserting the substrate of the second support into the first support.

According to one embodiment, the invention comprises one or more of the following features (alone or in combination).

According to one embodiment, the microstructures have at least one dimension less than 30 microns.

According to one embodiment, the substrate is made of silicon.

According to these arrangements, the master mold is produced by combining a 3D printing method for producing patterns with dimensions of sub-millimeters or millimeters and microstructures (preferably by photolithography or microetching on a silicon substrate, or by any other equivalent method for forming patterns of micrometers or sub-micrometers).

According to one embodiment, the three-dimensional printing of the first support comprises:

-before the step of inserting the substrate of the second support into the first support, a sub-step of stopping the printing of the first support according to the printed height of the first support; and

-continuing the sub-step of printing the first support from the height of the first support, the microstructure being aligned with the printed pattern of the first support, the continuing sub-step being performed after the inserting step.

According to an embodiment, during the substep of continuing the three-dimensional printing of the first support, the second support is partially encapsulated by the first support.

According to these arrangements, the second support is better secured to the first support, which is no longer movable relative to the first support. In another aspect, the size of the additional layer of the first support is not limited by the size of the encapsulated second support.

According to these arrangements, a silicon substrate is included. The silicon substrate is protected and is less likely to be broken when the first support member is inserted. The different parts are aligned with each other by construction and there are no interconnection problems between the different parts.

According to an alternative embodiment, the first support comprises a first portion and a second portion, the respective dimensions of the first portion and the second portion being adjusted according to the dimensions of the substrate of the second support, so that the substrate of the second support is inserted into a groove of the first support, the groove being formed between the first portion and the second portion of the first support, the step of three-dimensionally printing the first support comprising:

-a sub-step of printing a first portion of a first support; and

-a sub-step of printing a second portion of the first support.

This alternative embodiment has the advantage of overcoming some limitations of the exposure area of the 3D printer.

With the arrangement of this alternative embodiment, a larger frame can be created within the size constraints imposed by the 3D printer. It is also possible to reuse the first support for several silicon substrates. No stop step is required during 3D printing because all are assembled manually.

According to one embodiment:

-the first and second faces of the substrate are separated by the thickness of the substrate;

-stopping the printing of the first support once an overall height, equal to the sum of the thickness of the bottom of the printed first support plus the thickness of the substrate of the second support, is greater than the printed height of the first support by a value equal to or less than a predetermined threshold value;

inserting the substrate of the second support into the first support such that the second side of the substrate rests on the bottom of the first support;

-the method further comprises the sub-steps of:

-cutting the substrate from the second support around the microstructure after creating the second support, the dimensions of the first support being adjusted according to the dimensions of the cut substrate to accommodate the cut substrate.

According to one embodiment, the main mold generating step further comprises the sub-steps of:

-positioning a tool holder of the 3D printer in a determined position before the printing step;

-removing the tool holder from the 3D printer after the stopping of the printing step and before the inserting step;

-adding a resin on the first face of the substrate of the second support after the inserting step;

-positioning the tool holder in the determined position before continuing printing.

According to these arrangements, the step of inserting the second support into the first support becomes easier due to the nature of adjustment of the size of the second support relative to the size of the first support.

According to these arrangements, the step of adding the resin on the surface of the silicon substrate prevents bubbles from occurring during printing.

According to one embodiment, in the step of creating the second support, the formation of the microstructures comprises using one of photolithography, wet or dry wafer etching, 2-photon techniques, 3D printing with resolution comparable to photolithography.

According to one embodiment, the size of the first support is adjusted according to the size of the cut substrate, and the width and length of the first support are respectively larger than the width and length of the substrate cut from the second support by equal values within a prescribed tolerance.

According to an embodiment, the tolerance margins for the width and length of the first support are less than 0.25% of the width and less than 0.25% of the length of the first support, respectively.

According to one embodiment, the tolerance margin is determined according to the accuracy of the dimensions of the microstructure formed on the second support, i.e. a determined tolerance margin of 100 μm, for example.

According to an embodiment, the method further comprises the step of replicating the master mould to produce a first secondary mould from the master mould and a second secondary mould from the first secondary mould.

According to one embodiment, the replication step comprises a sub-step of producing a first secondary mould and a sub-step of producing a second secondary mould, the sub-step of producing the first secondary mould comprising a sub-step of positioning the primary mould inside the container and a sub-step of depositing a first auxiliary material in viscous phase on the primary mould in the container.

According to one embodiment, the first auxiliary material is cross-linkable, the first auxiliary material preferably being silicone rubber.

According to an embodiment, the sub-step of creating the first secondary mould further comprises a sub-step of evacuating the internal volume of the container in which the primary mould is placed, and a sub-step of annealing the first secondary material at room temperature (for example for 24 hours) before the sub-step of removing the first secondary mould formed by the deposited and cross-linked first secondary material.

According to one embodiment, the first auxiliary material remains flexible in the cross-linked phase, so that the first secondary mould formed by cross-linking the first auxiliary material is more easily removed without damaging the primary mould.

According to one embodiment, the first auxiliary material is a material compatible with the material used for creating the main mould.

According to an embodiment, the sub-step of creating the second secondary mould comprises the sub-step of depositing a second auxiliary material, for example in liquid phase, on the first secondary mould, the second auxiliary material being cross-linkable and rigid in the solid cross-linked phase.

According to an embodiment, the sub-step of creating the second secondary mould comprises a sub-step of removing the second secondary mould formed by the cross-linked second auxiliary material.

According to one embodiment, the second auxiliary material is a polyurethane resin.

According to an embodiment, the sub-step of creating the second secondary mould further comprises a sub-step of removing bubbles in the second secondary material with the injector cone, and an annealing sub-step, e.g. annealing at room temperature, e.g. for 2 hours, before the sub-step of removing the second secondary mould.

According to one embodiment, the microfluidic device comprises at least one layer, and the method comprises:

-a step of producing an encapsulation mold configured to cooperate with a second secondary mold in the production step of at least one layer; and

-a step of producing at least one layer.

The step of creating a package mold includes:

-a 3D printing sub-step of the main packaging mold,

-a sub-step of new replication of the primary encapsulation mold to produce a secondary encapsulation mold and an encapsulation mold based on the secondary mold encapsulation.

According to an embodiment, the sub-step of the new replication has the features described above for the replication step (starting from the main package mold until the package mold is realized).

Thus, according to an embodiment, the replication step comprises the creation of a secondary encapsulation mold and an encapsulation mold, the creation of the secondary encapsulation mold comprising the positioning of the encapsulation master mold within the container and the deposition of the first auxiliary material in viscous phase on the primary encapsulation mold in the container.

According to one embodiment, the first auxiliary material is cross-linkable, the first auxiliary material preferably being silicone rubber.

According to an embodiment, the creation of the secondary packaging mold further comprises evacuating the inner volume of the container in which the primary packaging mold is positioned, and annealing the first auxiliary material, for example at ambient temperature, for example for 24 hours, before removing the secondary packaging mold formed by the deposited and cross-linked first auxiliary material.

According to an embodiment, the first auxiliary material remains flexible in the cross-linking phase so as to be more easily removed from the secondary encapsulation mold formed by cross-linking the first auxiliary material without damaging the primary encapsulation mold.

According to an embodiment, the first auxiliary material is a material compatible with the material used for creating the main package mold.

According to an embodiment, the creation of the encapsulation mold comprises depositing a second auxiliary material (e.g. in liquid phase) on the secondary encapsulation mold, the second auxiliary material being cross-linkable and rigid in the solid cross-linked phase.

According to an embodiment, the creation of the encapsulation mold comprises removing the encapsulation mold formed by the cross-linked second auxiliary material.

According to one embodiment, the second auxiliary material is a polyurethane resin.

According to an embodiment, the production of the encapsulating mould further comprises removing the bubbles in the second auxiliary material with a syringe cone and an annealing treatment before removal from the encapsulating mould, for example at room temperature, for example for 2 hours.

According to an embodiment, the step of generating the at least one layer comprises:

-a sub-step of moulding said at least one layer by depositing moulding material between a second sub-mould and an encapsulating mould, the encapsulating mould and the second sub-mould being pressed against each other to ensure surface contact between a top element of the second sub-mould and a surface of the encapsulating mould;

-a substep of annealing the material between the second counter-mould and the encapsulating mould at a certain temperature for a determined period of time.

According to one embodiment, the layer is thermoformed, in contact on its first surface with the structures and/or microstructures present on the second secondary mould and in contact on its second surface with the structures and/or microstructures present on the encapsulating mould, which itself has been previously obtained by replicating the structured and/or microstructured encapsulating master mould.

According to one embodiment, the molding material is PDMS.

According to one embodiment, the annealing temperature is about 80 ℃ and the annealing time is about 1 hour.

According to one embodiment, the at least one layer comprises at least two layers, the layers of the at least two layers being mutually superposed and fixed after being aligned with each other, thereby forming the three-dimensional microfluidic device.

According to one embodiment, the pattern of one of the at least two layers is aligned with the pattern of another of the at least two layers to form nodes and microchannels distributed in three dimensions, the microchannels fluidly connecting the nodes.

According to one embodiment, the layers are fixed to each other by contact with an oxygen plasma, for example for one minute.

According to one embodiment, the method comprises a first step of computer-aided design of the at least one layer according to the three-dimensional architecture of the microfluidic device, and a second step of computer-aided design of the main mold and the main encapsulation mold according to the definition of the at least one layer.

According to one aspect of the invention, the invention also relates to a master mold for manufacturing a microfluidic device, the master mold comprising:

-a first support produced by 3D printing; and

-a second support comprising a substrate having a first face and a second face opposite to the first face, and a microstructure formed on the first face of the substrate.

The dimensions of the first support are adjusted according to the dimensions of the substrate to accommodate the substrate, the microstructures being aligned with the printed pattern of the first support.

According to an embodiment, the main mold comprises one or more of the following features (alone or in combination).

According to one embodiment, the microstructures have at least one dimension less than 30 microns.

According to one embodiment, the substrate is made of silicon.

According to one embodiment, the microstructures are formed by photolithography or a method with equivalent resolution.

According to an embodiment, the second support is partially surrounded by the first support.

According to these arrangements, the second support is better secured to the first support, which is no longer movable relative to the first support.

In another aspect, the size of the additional layer of the first support is not limited by the size of the encapsulated second support.

According to one embodiment, the master mould is obtained by implementing the method according to the invention.

According to one aspect of the invention, the invention also relates to a flexible secondary mould for manufacturing a microfluidic device, the flexible secondary mould being a replication of the primary mould according to one aspect of the invention in a cross-linkable first material, the cross-linkable first material being flexible after cross-linking.

According to one embodiment, the first material is compatible with the material of the master mould and is deposited on the master mould in a liquid or gel phase and is flexible after solid phase cross-linking.

According to an embodiment, the first material is one of silicone rubber, polyurethane, Polydimethylsiloxane (PDMS), glue, elastomer, flexible foam, plastic (plastiline).

According to one aspect of the invention, the invention also relates to a rigid counter-mold for manufacturing a microfluidic device, which is a replication of a flexible counter-mold according to one aspect of the invention in a cross-linkable second material, which is rigid after cross-linking.

According to one embodiment, the second material is compatible with the material of the flexible counter mould and is deposited on the flexible counter mould in a liquid or gel phase and is rigid after solid phase cross-linking.

According to an embodiment, the second material is one of a polyurethane resin, a cross-linkable resin, a hardening gel, a hardening foam, a plastic, a glue.

According to one aspect of the invention, the invention also relates to a layer for manufacturing a microfluidic device, which layer is a replication of a rigid secondary mould according to one aspect of the invention in a cross-linkable third material.

According to one embodiment, the third material is compatible with the material of the rigid counter-mould and is deposited on the rigid counter-mould in a liquid or gel phase.

According to an embodiment, the third material is one of polyurethane, Polydimethylsiloxane (PDMS), silicone rubber, glue, elastomer, flexible foam, plastic.

According to one aspect of the invention, the invention also relates to a microfluidic device comprising at least two layers according to one aspect of the invention, said at least two layers being placed and fixed to each other, the pattern of one of said at least two layers being aligned with the pattern of another of said at least two layers to form nodes and microchannels distributed in three dimensions, said microchannels fluidly connecting the nodes.

According to these arrangements, master molds not requiring the formation of microstructures (i.e. structures having a minimum dimension smaller than the resolution of the 3D printer, for example smaller than 30 μm) are produced by 3D printing, while those requiring the formation of microstructures are produced by a method according to the invention combining 3D printing with photolithography or a method with equivalent resolution and precision.

According to these arrangements, the second secondary mould and the respective encapsulating mould (preferably rigid) can be rapidly replicated in large numbers at the same level of detail as the main mould and the main encapsulating mould, respectively, based on the first secondary mould and the secondary encapsulating mould (preferably flexible).

Thus, the present invention enables rapid prototyping because it takes advantage of the design and manufacturing advantages of 3D printing. The longest time is: about 24 hours of manufacture of the main mould and the second support with microstructure, and about 24 hours of manufacture of the cavity in the form of the flexible first secondary mould. Replication of the mold in the form of the rigid second secondary mold requires only about 1 hour, and molding of the layers of the microfluidic device requires only about 2 hours.

The time cost of these last operations is low and they can be performed in parallel.

These arrangements make it possible to produce 3D microfluidic devices more efficiently and therefore much more complex than conventional 2D devices.

The two conventional techniques (combination of 3D printing and photolithography or equivalent resolution methods) make it possible to obtain both the very high resolution (below the micrometer scale) of the second method and the ease of use of 3D printing to produce centimeter-scale objects.

The initial equipment used to manufacture these apparatuses is standard and therefore inexpensive, about 50k —, by contrast to very high resolution 3D printing apparatuses of about 200k —. Furthermore, unlike conventional methods for manufacturing such devices, the replication of the mould and the manufacture of the device are carried out in controlled quantities, which makes it possible to do without any loss of material. The process according to the invention is therefore more economical.

The same structure of the different parts of the main mould and the manufacturing method can be standardized so that variations between each type of device have little impact on the design and manufacturing time.

The compatibility between PDMS and 3D printing material was not good due to the problem of non-crosslinking of the PMDS. However, by having intermediate steps of different materials, we can use the best materials suitable for our application, in our example PMDS is used for biology, but we can consider other materials (silicone) for other applications.

Unlike commercial 2D microfluidic devices currently on the market, the resulting devices cannot be replicated by stamping and reshaping, since the 3D stamp necessarily requires destruction of the molding during extraction of the stamp.

Drawings

For a correct understanding, embodiments of the invention are described with reference to the accompanying drawings, which show, by way of non-limiting example, embodiments of the device according to the invention. In the drawings, like reference numbers indicate similar elements or elements with similar functionality.

Fig. 1 is an illustration of sub-steps (F1a, F1b, F1c, F1D, F1e, F1F, F1g) of a production step of a 3D printing master mold;

fig. 2 is a representation of the base sheet of the second support F2b and the corresponding dimensions of the first support F2 a;

fig. 3 is a diagram of a first portion and a second portion of a first support according to a modification of a production step of a main mold by 3D printing;

fig. 4 is an illustration of sub-steps (F4a, F4b, F4c, F4D, F4e, F4F) of a modification of the production step of the main mold by 3D printing;

fig. 5 is a representation of the substrate of the second support and the corresponding dimensions of the first support according to a variant of the production step of the master mold by 3D printing;

FIG. 6 is a diagram of sub-steps (F6a, F6b, F6c, F6d, F6e) of the master mold replication step;

FIG. 7 is a schematic representation of the steps of creating a layer of microfluidic devices (F7a, F7b) and laminating two layers together to form a 3D microfluidic device (F7c, F7D);

fig. 8 is a schematic diagram of a method according to the present invention.

Detailed Description

The method according to the invention consists in coupling a microstructured substrate with a submillimeter or millimetre pattern printed directly and aligned by 3D printing to form a master mould which can then be replicated to create a secondary mould to be used for moulding the different layers of the final microfluidic device. The use of two molds in succession allows for molding compatibility of Polydimethylsiloxane (PDMS) elastomers, which are not crosslinked on the primary mold, but only on the secondary mold.

In general, a material is said to be crosslinkable if it is capable of being crosslinked, i.e. if it can be transformed from a pasty and viscous state of the material to a solid state of the material by polymerization of the material. The crosslinked phase represents the solid state of the material obtained after polymerization.

In general, mold compatibility is defined herein as the property of a material (e.g., PDMS) that allows the material to crosslink when in contact with another material (e.g., of a mold), without causing a chemical reaction or interference between the two materials in the absence of contact between the material and the other material. In this sense, it is important that the material of the secondary mold is compatible with PDMS.

The microfluidic device is divided into several layers, each of which is to be molded by the method. These PDMS layers will then be assembled by self-alignment to form a 3D microfluidic device.

A detailed description will now be given of an embodiment of the method according to the invention, starting from the step of generating the master mould, with reference to fig. 1, which comprises various sub-figures F1a, F1b, F1c, F1d, F1e, F1F and F1g, in fig. 2 also different sub-figures F2a and F2b, and with reference to fig. 8.

The master mold 1 shown in F1g includes a first support 2 and a second support 8, and the second support 8 includes a substrate 3 and microstructures 4 formed on one face of the substrate 3.

The substrate 3 of the second support 8 is made of silicon, for example.

During a first step 1011, microstructures 4 are formed on the surface of one face of the substrate 3, for example using conventional techniques, such as silicon lithography. The term "microstructure" refers to a structured shape having at least one dimension less than 30 microns.

The production of the master mould comprises the following steps:

printing 1012 the three-dimensional form of the first support 2 on a 3D printer 7 (as shown in fig. 1(F1a and F1b to F1F)); for example 3D printing with printing resin, the dimensions of the first support 2 being adjusted according to the dimensions of the substrate 3 of the second support 8 to allow the substrate 3 to be accommodated;

inserting 1014 the substrate of the second support 8 into the first support.

According to an embodiment of the method according to the invention, the printing step 1012 of the three-dimensional (3D) form of the first support 2 comprises:

before the step 1014 of inserting the substrate of the second support 8 into the first support 2, the sub-step 1013 of stopping the 3D printing of the first support 2 according to the height of the printed first support 2; and

continuing the sub-step 1015 of printing the first support from the height of the first support 2, the microstructures 4 being aligned with the pattern of the printed first support 2, the 3D printing continuing sub-step being carried out after the inserting step 1014.

Thus, as shown at F1c in fig. 1, the 3D printing of the first support is stopped 1013 to allow the second support 8 to be inserted 1014 into the first support 2. According to this embodiment, the stopping of the 3D printing is according to the height H of the edge of the first support_totTo be determined. For example, when the height H is_totGreater than the thickness E of the bottom of the first support 2_fAnd the thickness of the substrate of the second support 8, then the 3D printing of the first support is interrupted and the second support 8 is inserted inside the first support 2 before the 3D printing of the first support 2 is continued.

Advantageously, the height H of the edge is such that when 3D printing is stopped_totIt will be sufficient to allow the substrate 3 to be encapsulated. Therefore, it is conceivable that the height H is set as the height_tot3D printing is stopped at 3mm 1013, that is, there are more than 99 3D printed levels for 30 μm printed levels per level; this will allow the edge to have sufficient stiffness to avoid binding on the substrate.

According to one embodiment, before the second support 8 is inserted 1014 into the first support 2, the second support 8 is cut 1011bis around the microstructure 4, the dimensions of the first support 2 being adjusted according to the dimensions of the cut substrate 3 to accommodate the cut substrate 3.

According to one embodiment, prior to the printing step 1012, the tool holder 5 of the 3D printer 7 is positioned 1011ter at a determined location, which may be replicated after the tool holder 5 is removed from the 3D printer 7.

After the step of stopping the printing 1013, the 1013bis toolhead 5 is taken out of the 3D printer, as shown by F1D in fig. 1, in order to insert 1014 the second support 8 into the first support 2.

Then, after the inserting step 1014, resin may be added 1014bis to the first side of the substrate of the second support 8.

Then, before continuing the 3D printing 1015, as shown by F1F in fig. 1, the tool rest 5 may be repositioned to a determined position on the 3D printer 7, as shown by F1c in fig. 1.

According to one embodiment, the dimensions of the first support 2 are adjusted according to the dimensions of the cut substrate 3; width l of the first support₂And the length L2 is correspondingly greater than the width and length of the substrate cut from the second support 8 by a value equal to the determined tolerance margin. Width l of the first support₂And length L2 are typically less than the width L of the first support, respectively₂0.25% and the length L of the first support₂0.25% of.

According to one embodiment, the tolerance margin is determined according to the accuracy of the dimensions of the microstructure formed on the second support 8. The tolerance margin may be, for example, 100 μm.

According to an alternative embodiment or variant, which will now be described with reference to fig. 3, 4 and 5, the first support comprises a first portion a and a second portion B, the respective dimensions of which are adjusted according to the dimensions of the base sheet of the second support, so that the base sheet of the second support fits into a groove E of the first support, the groove being formed between the first portion and the second portion of the first support.

The three-dimensional printing step of the first support comprises:

-a 3D printing sub-step of a first portion a of the first support; and

-a 3D printing sub-step of the second portion B of the first support.

The advantage of this variant is that the limitation of the exposure area of the 3D printer is overcome.

According to an embodiment of this variant, the dimensions of the first portion a of the first support 2 are determined by the dimensions of the second support to be inserted. Thus:

each edge of the first portion A has a variable l_bordThe size of the glass fiber is measured,advantageously identical, wide enough to position the second support strictly in the centre of the square including the allowance for tolerances; these tolerances allow the insertion of the substrate of the second support to be adjusted to align the pattern to be three-dimensionally printed with the lithographic pattern; these tolerance margins also allow for limitations associated with the dimensional accuracy of the substrate. For example, in the configuration shown in FIG. 5, the length L of the substrate_shAre selected to be the same to have square shaped devices, again by way of example, select L_chip＝35mm，L_substrat＝40mm，L_sh50mm and L_sh40 mm. Therefore, in this case, the insertion tolerance margin is limited by the cutting accuracy of the silicon support, which is 50 μm. This tolerance must be taken into account when designing the dimensions of the lithographic pattern (as shown in fig. 5).

The embedding depth E of the substrate of the second support in the second portion B of the first support is equal to the thickness of the substrate, with a substrate tolerance h_substratOverlap with second support_bord. Given here as an example, the thickness of the substrate of the second support is h_substrat550 μm and overlapping width of its edge is l_bord＝2.5mm。

A female plug FF is provided on the periphery of the first portion a of the first support and is configured to receive a male plug FM provided on the second portion B of the first support; the diameter d of each female plug FF takes into account the tolerances with respect to the corresponding male plug FM_pin2mm, height h_pin＝2.1mm。

The substrate of the second support is cut to the desired size, for example with a circular saw.

As shown in F4a of fig. 4, the substrate of the second support is positioned and fixed in a groove formed and sized on a tool holder of the 3D printer. The recess is dimensioned such that, for example, a substrate can be received from the second support with an accuracy of at least 50 μm in the plane of the tool holder and with an accuracy of at least 5 μm in a plane perpendicular to the plane of the holder. If the printer has a surface detection mode, no suitable tool holder is needed, since the surface of the silicon holder will be used as a reference.

The tool holders are positioned in a configuration that allows the tool holders to be aligned with the pattern to be printed. For example, it may be pushed to a stop position, as shown at F4b in FIG. 4.

As shown in F4c of fig. 4, 3D printing of the pattern 9 of the first support was printed with a 3D printer.

As shown in F4D, F4e, and F4F of fig. 4, after the tool holder has been detached from the 3D printer, and the second support with the 3D printed pattern 9 has been detached from the tool holder, the second support with the 3D printed pattern 9 is positioned in the anchor of the first portion a of the first support, between the first portion a and the second portion B of the first support.

As shown in F4d, F4e, and F4F of fig. 4, the male plug FM of the second portion B of the first support is configured to be inserted into the female plug FF of the first portion a of the first holder to enclose the substrate of the second support.

Thus, according to the embodiment just described, the substrate of the second support with the 3D printed pattern is anchored in the first portion a of the first support, while the second portion B of the first support serves as a packaging. However, according to another variant, the second portion B of the first support (instead of the first portion a) may be used as a packaging, while the first portion a of the first support is configured to embed the base sheet of the second support therein.

According to several embodiments and with reference to fig. 1, 2, 3, 4, 5 and 8, after the step of generating the main mould just described, according to a supplementary embodiment, a step 102 of duplicating the main mould 1 to generate a first secondary mould 11 based on the main mould 1 and a second secondary mould 12 based on the first secondary mould 11 is also included. The step 102 of replicating the master mold will now be described in detail with reference to fig. F6a, F6b, F6c, F6d, F6e in fig. 6.

According to an embodiment, the sub-step of creating the first secondary mould comprises a sub-step of positioning the primary mould inside the container 13, as shown in F6a of fig. 6, and a sub-step of depositing the first secondary material 14 in viscous phase on the primary mould in the container 13, as shown in F6b of fig. 6.

The first auxiliary material 14 is a cross-linkable material, preferably silicone rubber.

The sub-step of creating the first secondary mould 11 also comprises a sub-step of evacuating the internal volume of the container 13 in which the primary mould is positioned, and a sub-step of annealing the first secondary material 14 at ambient temperature, for example for 24 hours, before the sub-step of removing the first secondary mould 11 formed by the first deposited and cross-linked secondary material 14, shown at F6c of fig. 6.

According to one embodiment, first auxiliary material 14 remains flexible in the cross-linked phase; this makes it easier to remove the first sub-mold 11 formed by cross-linking the first auxiliary material 14 without damaging the main mold.

According to one embodiment, the first auxiliary material 14 is a material compatible with the material used to create the main mold.

According to an embodiment, the sub-step of producing the second secondary mould 12 comprises a sub-step of depositing a second auxiliary material 15 (for example in liquid phase) on the first secondary mould 11, as illustrated by F6d of fig. 6, the second auxiliary material 15 being cross-linkable and rigid in the solid cross-linked phase.

According to an embodiment, the sub-step of creating the second secondary mould 12 comprises the sub-step of removing the second secondary mould 12 formed by the second cross-linking auxiliary material 15, as illustrated by F6e of fig. 6.

According to one embodiment, the second auxiliary material 15 is a polyurethane resin.

According to an embodiment, the sub-step of creating the second secondary mould 12 further comprises a sub-step of removing air bubbles in the second secondary material 15 with an injector cone, and an annealing sub-step, for example at room temperature, for example for 2 hours, before the sub-step of removing the second secondary mould 12.

According to a supplementary embodiment shown in fig. 7, after the step 102 of duplicating the main mould 1 to produce a first secondary mould 11 and then a second secondary mould 12 on the basis of the main mould 1, the method according to the invention further comprises a step 104 of producing one or more layers 17, 18; the layers 17, 18 are intended to be superposed to form a microfluidic circuit 20.

According to one embodiment, the step 104 of creating one or more layers 17, 18 is preceded by the step 103 of creating the encapsulation mold 16, as shown at F7a of fig. 7.

The generating step 103 of the package mold 16 includes:

a sub-step 1031 of 3D printing of the main packaging mold;

a sub-step 1032 of new replication of the main packaging mold, to generate the secondary packaging mold and to generate the packaging mold 16 based on the secondary packaging mold.

The sub-step 1032 of the new replication has the features described above for the replication step, according to an embodiment, starting from the main packaging mold until the packaging molds 12, 16 are realized.

Thus, according to the embodiment already described and illustrated in fig. 6, the new replication step comprises the creation of the secondary packaging mould 11 and the packaging moulds 12, 16, the creation of the secondary packaging mould 11 comprising the positioning of the primary packaging mould 1 within the container 13 and the deposition of the first auxiliary material 14 in viscous phase on the primary packaging mould 1 in the container 13.

According to one embodiment, the first auxiliary material 14 is crosslinkable, the first auxiliary material 14 preferably being silicone rubber.

According to an embodiment, the creation of the secondary packaging mold 11 also comprises evacuating the internal volume of the container 13 in which the primary packaging mold 1 is positioned, and annealing the first auxiliary material 14 at room temperature, for example for 24 hours, before removing the secondary packaging mold 11 formed by the deposited and cross-linked first auxiliary material 14.

According to an embodiment, first auxiliary material 14 remains flexible in the cross-linking phase so as to be more easily removed from secondary encapsulation mold 11 formed by cross-linking first auxiliary material 14 without damaging primary encapsulation mold 1.

According to an embodiment, the first auxiliary material 14 is a material compatible with the material used for creating the main package mold 1.

According to an embodiment, the creation of the encapsulation mold 12, 16 comprises depositing a second auxiliary material 15 (for example in liquid phase) on the secondary encapsulation mold 11, the second auxiliary material 15 being cross-linkable and rigid in the solid cross-linked phase.

According to an embodiment, the creation of the encapsulation mold 12, 16 comprises removing the encapsulation mold 12, 16 formed by the cross-linked second auxiliary material 15.

According to one embodiment, the second auxiliary material 15 is a polyurethane resin.

According to an embodiment, the generation of the encapsulating mould 12, 16 further comprises removing the bubbles in the second auxiliary material 15 with a syringe cone and an annealing treatment, for example at room temperature, for example for 2 hours, before removing the encapsulating mould 12, 16.

The production step 103 of the encapsulation dies 12, 16 is followed by a production step 104 of the first layer 17 of the microfluidic device 20. As shown in fig. 7, the generating step 104 includes:

a sub-step 1041 of moulding at least one layer produced by depositing moulding material between the second sub-mould 12 and the encapsulation mould 12, 16, the encapsulation mould 12, 16 and the second sub-mould 12 being pressed against each other to ensure surface contact between the upper element of the second sub-mould 12 and the lower surface of the encapsulation mould 12, 16;

a sub-step 1042 of annealing the moulding material between the second sub-mould 12 and the encapsulating moulds 12, 16, wherein the annealing is carried out at a determined temperature for a period of time.

According to one embodiment, the molding material is PDMS.

According to one embodiment, the annealing temperature is about 0 ℃ and the annealing time is about 1 hour.

The aforementioned steps of the method according to the invention are repeated as many times as the number of layers 17, 18 to be produced to form the microfluidic circuit 20.

The layers 17, 18 are stacked and fixed to each other after being aligned with respect to each other to form a three-dimensional microfluidic device.

According to one embodiment, the pattern of one of the at least two layers is aligned with the pattern of another of the at least two layers to form nodes and microchannels distributed in three dimensions, the microchannels fluidly connecting the nodes.

According to one embodiment, the layers are fixed to each other by contact with an oxygen plasma, for example for one minute.

According to one embodiment, the layers 17, 18 of the microfluidic device 20 are defined during a first step 101bis of computer-aided design as a function of the three-dimensional structure of the microfluidic device 20; in a second step 101ter of computer-aided design, a main mould 1 and a main encapsulation mould are defined for each layer 17, 18.

According to one aspect, the invention relates to a master mold 1 obtained by a method according to the invention, comprising:

a first support 2, produced by 3D printing; and

a second support 8 comprising a substrate 3 and microstructures 4, the substrate 3 having a first face and a second face opposite the first face, the microstructures being formed on the first face of the substrate 3, the dimensions of the first support 2 being adjusted to the dimensions of the substrate 3 to accommodate the substrate 3, the microstructures 4 being aligned with the printed pattern of the first support 2.

According to one embodiment, the microstructures have at least one dimension less than 30 microns.

According to one embodiment, the substrate is made of silicon.

According to one embodiment, the microstructures are formed by photolithography or a method with equivalent resolution.

The master mould is obtained by implementing the method according to the invention.

According to another aspect, the invention also relates to a flexible counter mold 11 for manufacturing a microfluidic device 20, the flexible counter mold 11 being a replica of the main mold 1 in a first cross-linkable material, which is flexible after cross-linking.

According to one embodiment, the first cross-linkable material which is flexible after cross-linking is one of silicone rubber, polyurethane, elastomer, flexible foam, plastic.

According to another aspect, the invention also relates to a rigid counter-mold 12 for manufacturing a microfluidic device 20, the rigid counter-mold 12 being a replica of the flexible counter-mold 11 according to an aspect of the invention in a second cross-linkable material, the second cross-linkable material being rigid after cross-linking.

According to an embodiment, the second cross-linkable material being rigid after cross-linking is one of a polyurethane resin, a cross-linkable resin, a hardened gel, a hardened foam, a plastic, a glue.

According to another aspect, the invention also relates to a layer 17, 18 for manufacturing a microfluidic device 20, said layer 17, 18 being a replica of the rigid counter mould 11 in a third cross-linkable material.

According to an embodiment, the third crosslinkable material is one of Polydimethylsiloxane (PDMS), silicone, adhesive, elastomer, flexible foam, plastic.

According to another aspect, the invention also relates to a microfluidic device 20 comprising at least two layers 17, 18 according to one aspect of the invention, said at least two layers 17, 18 being placed and fixed to each other, the pattern of one of said at least two layers being aligned with the pattern of the other of said at least two layers to form nodes distributed in three dimensions and microchannels, said microchannels fluidly connecting the nodes.

According to these arrangements, the master molds not required to form microstructures, i.e. structures with a minimum dimension smaller than the resolution of the 3D printer (for example smaller than 30 μm), are produced by 3D printing, while those required to form microstructures are produced by the method according to the invention, which combines 3D printing with photolithography or a method with precision and equivalent resolution.

According to these arrangements, the second secondary mould and the corresponding encapsulating mould (preferably rigid) can be rapidly replicated in large numbers at the same level of detail as the main mould and the main encapsulating mould, based on the first secondary mould and the secondary encapsulating mould (preferably flexible), respectively.

Thus, the present invention enables rapid prototyping because it takes advantage of the design and manufacturing advantages of 3D printing. The longest time is: about 24 hours of manufacture of the primary mould and the second support with microstructure, and about 24 hours of printing in the form of the first flexible secondary mould. Replication of the mold in the form of the second rigid counter mold takes only about 1 hour and molding of the layers of the microfluidic device takes only about 2 hours.

The time cost of these last operations is low and they can be performed in parallel.