CN116214779A

CN116214779A - Microporous membrane forming and manufacturing method

Info

Publication number: CN116214779A
Application number: CN202310109774.7A
Authority: CN
Inventors: 韩超; 刘瑞
Original assignee: Guangzhou Anfang Biotechnology Co ltd
Current assignee: Guangzhou Anfang Biotechnology Co ltd
Priority date: 2023-02-10
Filing date: 2023-02-10
Publication date: 2023-06-06

Abstract

The invention discloses a microporous membrane forming and manufacturing method, which comprises the following steps: firstly, manufacturing a microporous membrane mould, copying the structure of the microporous membrane mould by adopting a soft material to obtain a copying template, then, tightly attaching the copying template to a glass substrate to form an injection molding space, injecting photosensitive curing adhesive into the injection molding space, and putting the injection molding space into a high-pressure environment; and then solidifying and forming the photosensitive solidified glue by ultraviolet light to prepare a microporous membrane, finally separating the replication template from the glass substrate, and stripping the microporous membrane from the glass substrate. According to the microporous membrane molding manufacturing method, the photosensitive curing adhesive injected into the injection molding space can be rapidly and completely filled in the injection molding space through the high-pressure environment, bubbles and gaps can be completely avoided from being generated at the inner structure of the injection molding space, the injection molding speed is high, the operation is simple, and the molding efficiency is high. The method can be applied to the preparation of micro-nano through hole structures.

Description

Microporous membrane forming and manufacturing method

Technical Field

The invention relates to the technical field of capillary flow micro-nano injection molding, in particular to a microporous membrane molding and manufacturing method.

Background

When rare cells in a blood sample are counted, the microporous membrane is required to be used for separating, capturing and enriching the rare cells in the blood sample, so that enriched cell sample liquid with higher purity is obtained, the detection accuracy is improved, the detection speed is increased, the reagent cost and the equipment cost are reduced, and the detection engineering is facilitated.

Fine machining of conventional dimensions typically uses CNC or 3D printing, but micro-nano structures (below 10 um) typically need to be prepared using photolithographic and etching methods. The injection molding of micro-nano structures (especially through hole structures) always adopts standard etching and stripping methods, and the method has high requirements on instruments, long molding time and low yield and is not suitable for common laboratories.

In the prior art, a negative pressure adsorption mode at an outlet is adopted to promote the photo-curing adhesive to fill the soft mold. The method is easy to generate bubbles and gaps, and once the dense micro-nano structure exists, the resistance of the inner space is very large, so that the glue cannot fill the micro-nano structure space, the forming efficiency is extremely low, and the application range is low.

Disclosure of Invention

The present invention is directed to a method for forming and manufacturing microporous membranes, which solves one or more of the technical problems of the prior art, and at least provides a beneficial choice or creation.

The technical scheme adopted for solving the technical problems is as follows:

a microporous membrane forming and manufacturing method comprises the following steps:

step S1, manufacturing a microporous membrane mould;

s2, copying the structure of the microporous membrane mould by adopting a soft material to obtain a copying template;

step S3, the copying template is tightly attached to the glass substrate to form an injection molding space;

s4, injecting and adding photosensitive curing glue into the injection molding space, and placing the injection molding space into a high-pressure environment;

s5, solidifying and forming the photosensitive curing glue by ultraviolet light to prepare a microporous membrane;

step S6, separating the replication template from the glass substrate, and peeling the microporous membrane from the glass substrate.

The microporous membrane forming and manufacturing method provided by the invention has at least the following beneficial effects: preparing a concave pattern structure required by the microporous membrane on a microporous membrane mould, copying to obtain a copy template with a corresponding convex pattern structure, forming a micropore injection molding space through the copy template and the glass substrate, enabling the photosensitive curing adhesive injected into the injection molding space to rapidly and completely fill the injection molding space through a high-pressure environment, and finally carrying out ultraviolet curing on the photosensitive curing adhesive to obtain the microporous membrane. The preparation scheme adopts whole malleation to promote the packing of glue, can avoid the internal structure department in space of moulding plastics to produce bubble and space completely, and the speed of moulding plastics is fast, easy operation, and shaping efficiency is high.

As a further improvement of the above technical solution, the step S1 includes:

s11, preparing a mask;

step S12, uniformly coating positive photoresist on the surface of the substrate and baking;

and S13, after the substrate is cooled to room temperature, covering the mask plate on the substrate, and exposing, baking and developing.

By adopting the technical scheme, various functional patterns are manufactured on a film, plastic or glass matrix material by adopting an optical mask and are precisely positioned so as to be used for selectively exposing a photoresist coating to form a micropore structure.

As a further improvement of the above technical solution, in step S11, the mask is manufactured by performing photolithography according to the hole diameters, the number and the arrangement of the through holes required by the microporous membrane.

As a further improvement of the above technical solution, in the step S12, the substrate is treated with the TI-Primer reagent, and then the positive photoresist is coated.

Through the technical scheme, the TI-Primer reagent can carry out the adhesion treatment on the substrate, so that the adhesion between the positive photoresist and the substrate is improved, and the abnormality of the subsequent process is avoided.

As a further improvement of the above technical scheme, the substrate is spin-coated with TI-Primer reagent at 2000 to 4000rpm for 18 to 22 seconds, and then baked and fused.

As a further improvement of the above technical solution, in step S12, the substrate coated with the positive photoresist is baked for 10min at 120 to 135 ℃ using an oven or baked for 2min at 115 to 125 ℃ by placing on a hot plate.

As a further improvement of the above technical solution, in the step S12, the positive photoresist is applied to a thickness of 18 to 22 μm.

As a further improvement of the above technical solution, in step S2, the soft material is PDMS, the microporous membrane mold has a concave pattern structure, and the replication template has a convex pattern structure.

As a further improvement of the above technical scheme, in the step S5, the intensity of the ultraviolet light is 5 to 13mW/cm ² The exposure time was 20 to 15 seconds.

As a further improvement of the above technical solution, in the step S4, the pressure in the high pressure environment is 0.2Mpa to 0.4Mpa.

Drawings

The invention is further described below with reference to the drawings and examples;

FIG. 1 is a schematic flow chart of an embodiment of a method for forming a microporous membrane according to the present invention;

FIG. 2 is a schematic cross-sectional view of a mask according to an embodiment of the present invention;

FIG. 3 is a schematic cross-sectional view of a substrate according to an embodiment of the present invention;

FIG. 4 is a schematic cross-sectional view of a substrate coated with a positive photoresist according to one embodiment of the present invention;

FIG. 5 is a schematic view of an exposure process of a microporous membrane mold according to an embodiment of the present invention;

FIG. 6 is a schematic cross-sectional view of one embodiment of a microporous membrane mold provided by the present invention;

FIG. 7 is a schematic diagram of a method for forming a microporous membrane according to an embodiment of the present invention, in which PDMS is cast onto a microporous membrane mold;

FIG. 8 is a schematic cross-sectional view of one embodiment of a replication template provided by the present invention;

FIG. 9 is a schematic cross-sectional view of a replica mold and a glass substrate according to an embodiment of the present invention;

FIG. 10 is a schematic illustration of an injection molding process according to an embodiment of the present invention;

FIG. 11 is a schematic view of a cured structure of a microporous membrane after injection molding according to an embodiment of the present invention;

FIG. 12 is a schematic cross-sectional view of one embodiment of a finished film and glass substrate provided by the present invention;

FIG. 13 is a schematic cross-sectional view of one embodiment of a finished film of microporous structure provided by the present invention.

In the figure: 100. a microporous membrane mold; 110. masking plate; 120. a substrate; 130. a positive photoresist; 200. copying the template; 300. a glass substrate; 400. photosensitive curing glue; 500. and (5) a finished film.

Detailed Description

Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein the accompanying drawings are used to supplement the description of the written description so that one can intuitively and intuitively understand each technical feature and overall technical scheme of the present invention, but not to limit the scope of the present invention.

In the description of the present invention, it should be understood that references to orientation descriptions such as upper, lower, front, rear, left, right, etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience of description of the present invention and to simplify the description, and do not indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.

In the description of the present invention, if there is a word description such as "a plurality" or the like, the meaning of a plurality is one or more, and the meaning of a plurality is two or more, and greater than, less than, exceeding, etc. are understood to not include the present number, and above, below, within, etc. are understood to include the present number.

In the description of the present invention, unless explicitly defined otherwise, terms such as arrangement, installation, connection, etc. should be construed broadly and the specific meaning of the terms in the present invention can be reasonably determined by a person skilled in the art in combination with the specific contents of the technical scheme.

Referring to fig. 1 to 13, the microporous membrane molding and manufacturing method of the present invention makes the following examples:

step one, a microporous membrane mold 100 is fabricated.

And step two, copying the structure of the microporous membrane mould 100 by adopting a soft material to obtain a copying template 200.

Step three, the replication template 200 is tightly attached to the glass substrate 300 to form an injection molding space;

and step four, injecting and adding photosensitive curing glue 400 into the injection molding space, and putting the injection molding space into a high-pressure environment.

And fifthly, curing and forming the photosensitive curing adhesive 400 by ultraviolet light to prepare the microporous membrane.

Step six, separating the replication template 200 from the glass substrate 300, and peeling the microporous film from the glass substrate 300.

The required concave pattern structure is prepared on the microporous membrane mold 100, the replication template 200 with the corresponding convex pattern structure is obtained by replication, then an injection molding space for micropore injection molding is formed by the replication template 200 and the glass substrate 300, the photosensitive curing adhesive 400 injected into the injection molding space can be rapidly and completely filled in the injection molding space by a high-pressure environment, and finally the photosensitive curing adhesive 400 is subjected to ultraviolet curing to obtain the microporous membrane. Adopt whole malleation to promote glue to fill, can avoid producing bubble and space in the inner structure department in space of moulding plastics completely, it is fast to mould plastics, easy operation, and shaping efficiency is high.

Step one, specifically: first, as shown in fig. 2, a reticle 110 is prepared by photolithography processing according to the hole diameters, the number and the arrangement of the through holes required for the microporous membrane.

Reticle 110 is a commonly used pattern reticle for lithographic processes in micro-nano processing techniques. The pattern structure can be obtained by plate making process, and the common processing equipment is direct writing type photoetching equipment, such as a laser direct writing photoetching machine, an electron beam photoetching machine and the like. In this example, the microporous membrane for cell separation, capture and enrichment adopts a through-hole structure.

Then, as shown in fig. 3 and 4, the substrate 120 is treated with TI-Primer reagent, and then the positive photoresist 130 is coated and baked.

For most photoresists and silicon-based substrates 120, adhesion between the substrate 120 and the photoresist is generally sufficient. However, for some substrates 120 such as sapphire, gallium nitride, gallium arsenide, and even noble metal films, the adhesion between such substrates 120 and photoresist is often less than ideal, which causes problems such as "cracking" and even rinsing in the subsequent photolithography development step, and therefore, the process must be improved, which step is called adhesion-promoting treatment or adhesion-promoting treatment.

In this embodiment, the Si substrate 120 or the glass substrate 120 is employed. Silica, as well as most metals in the form of oxides that naturally oxidize the surface of quartz, glass or silicon, form polar OH bonds on their surface after exposure to the atmosphere at a certain humidity for a sufficient period of time. Such a substrate 120 is hydrophilic and thus has a poor affinity for nonpolar or low polar resin molecules of the photoresist.

The TI-Primer reagent is an adhesion promoter based on spin coating, forms a hydrophobic surface on the surface of the isolation substrate 120, improves the wettability and the adhesion to photoresist, and can effectively improve the adhesion between the Si substrate 120 or the glass substrate 120 and the photoresist. Specifically, the substrate 120 is spin-coated at 2000 to 4000rpm for about 20 seconds of TI-Primer, and baked at 130 ℃ for 10 minutes by using an oven or placed on a hot plate for 2 minutes at 120 ℃.

In particular, the TI-Primer reagent contains titanium and is not useful in titanium-sensitive materials or processes. In other embodiments, other adhesion promoters such as AR300-80 or HMDS (hexamethyldisilane) may also be used.

Positive photoresist 130 is uniformly coated on the substrate 120 after the adhesion-increasing process is completed and baked. Optionally baking at 120-135deg.C for 10min with oven, or baking at 115-125deg.C for 2min on hot plate. In this embodiment, the substrate 120 is baked at 126 ℃ for 10min by using an oven, so as to implement the curing treatment of the photoresist.

In this embodiment, the positive photoresist 130 has a smear thickness of 18 to 22 μm, preferably 20 μm. The positive photoresist 130 may be coated by spin coating at a spin speed of 2000 to 4000rpm for 30 to 60 seconds, for example, 40 seconds, 45 seconds, or 50 seconds. The positive photoresist 130 may be selected to have a model number of AZ40XT.

As shown in fig. 5, after the baked substrate 120 is cooled to room temperature, the mask 110 is aligned to and covered with the substrate 120 solidified with the photoresist, and the substrate 120 is exposed by light source in combination with the regulation of light by the mask. The exposure light source can adopt a common white light source or a UV light source. In this embodiment, UV light source is used for ultraviolet exposure. The wavelength of the ultraviolet light of the ultraviolet exposure is 365nm, and the intensity of the ultraviolet light is 7.3mW/cm ² The uv exposure time was 15 seconds.

The size and shape of the exposure pattern can be adjusted by adjusting the exposure dose, so that different nano patterns can be prepared. In other embodiments, the exposure process may select a different light source for exposure. When the exposure dose is low, the light intensity of 40mW/cm can be selected ² The exposure time was 10s. When the exposure dose is high, the light intensity of 105mW/cm can be selected ² The exposure time was 10s.

As shown in fig. 6, after the exposure process is completed, the mask plate 110 is removed, and the substrate 120 is subjected to a developing process, so that a microporous pattern structure, that is, a microporous membrane mold 100, is obtained on the substrate 120. The development process is performed in a developer solution, and the development time depends on specific parameters of the developer solution and the positive photoresist 130. Optionally, development is carried out in AZ826MIF developer for 50 seconds. In some embodiments, the substrate 120 may be baked again after the exposure process is completed and before the development process is performed.

In the second step, the concave pattern structure of the microporous film mold 100 is replicated by a soft material, so as to obtain a replication template 200 having a convex pattern structure corresponding to and complementary with the microporous film mold 100.

Specifically, in this embodiment, PDMS is used as the soft material. PDMS (Polydimethylsiloxane) is a high molecular polymer, also known as polydimethylsiloxane or simethicone. According to different relative molecular masses, the appearance is from colorless transparent volatile liquid to extremely high viscosity liquid or silica gel, the transparent silicone oil is odorless, has high transparency, heat resistance, cold resistance, small viscosity change along with temperature, water resistance, small surface tension, thermal conductivity coefficient of 0.134-0.159W/(m.K), light transmittance of 100 percent, and simethicone is nontoxic and odorless, and has physiological inertia and good chemical stability. The electric insulation, weather resistance and hydrophobicity are good, and the anti-shearing capability is very high, and the anti-shearing agent can be used for a long time at the temperature of minus 50 ℃ to 200 ℃.

As shown in fig. 7 and 8, the PDMS solution is poured onto the microporous membrane mold 100, and after curing, the template 200 is released from the mold.

Since PDMS is a colorless, viscous liquid at room temperature and cannot be cured, a specific curing agent is added. The PDMS solution was prepared by mixing PDMS prepolymer and curing agent in a mass ratio of 10:1. After sufficient agitation, a large number of bubbles appear in the solution and are evacuated in a vacuum drum (which may also be left for more than 40 minutes) until the mixture is completely evacuated.

In order to obtain a PDMS template with uniform thickness, a multi-spin coating mode is adopted in the embodiment. A small amount of PDMS solution was then slowly poured onto the microporous membrane mold 100, allowed to slowly disperse and remove any air bubbles, and the centrifuge speed and time adjusted accordingly. After applying the monolayer, the film is allowed to stand for about 1 minute and then soft baked, and bubbles are found before heating, which can form during heating if the bubbles are not completely expelled. After the spin coating process was completed, it was baked in an oven at 65℃for 2 hours. Finally, a flexible PDMS replica mold 200 having a thickness of about 450 μm was obtained, the convex pattern structure of one side surface of which was opposite in shape to the concave pattern structure on the microporous membrane mold 100.

As shown in fig. 9, in the third step, the replica template 200 is attached to the glass substrate 300, and the convex pattern structure on the replica template 200 made of PDMS can be automatically attached to the flat surface of the glass substrate 300. The convex pattern structure of the replication template 200 forms an injection molding space with the glass substrate 300. In the first step, a glue injection part structure is reserved when the microporous membrane mold 100 is manufactured, so that the injection space is provided with a glue injection port.

As shown in fig. 10 and 11, the photosensitive curing adhesive 400 is added and injected into the injection space through the adhesive injection port, and is placed into a high pressure environment. By high-pressure assistance, the photosensitive curing adhesive 400 added to the adhesive injection port can fill all gaps and corners of the injection molding space faster, so that the injection molding time is greatly shortened, and the molding rate is improved.

The pressure of the high-pressure environment is 0.2Mpa to 0.4Mpa. In this embodiment, the high-pressure environment is provided by an air compressor, and the air compressor is communicated with the glue injection port of the injection molding space.

The curing principle of the photosensitive curing adhesive 400 is that the photoinitiator (or photosensitizer) in the curing adhesive generates active free radicals or cations after absorbing ultraviolet light under the irradiation of ultraviolet light to initiate chemical reactions of monomer polymerization and crosslinking, so that the curing adhesive is converted from a liquid state to a solid state within a few seconds.

In this embodiment, in the curing process of the fifth step, the ultraviolet light intensity is 5 to 13mW/cm ² The exposure time is 20 to 10 seconds, specifically, 365nm ultraviolet light with intensity of 7.3mW/cm can be selected ² The exposure time was 15 seconds.

As shown in fig. 12 and 13, the photosensitive curing adhesive 400 is cured and formed under the action of ultraviolet light to form a microporous membrane structure, in the sixth step, the replica mold 200 made of PDMS is separated from the glass substrate 300, and the formed microporous membrane 500 is peeled from the glass substrate 300 by a blade

In the description of the present specification, reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present invention have been shown and described, various changes, modifications, substitutions and alterations can be made herein by one having ordinary skill in the art without departing from the spirit and scope of the present invention as defined by the following claims and the equivalents thereof.

Claims

1. A microporous membrane forming and manufacturing method is characterized in that: the method comprises the following steps:

step S1, manufacturing a microporous membrane mould;

2. The method for forming and manufacturing the microporous membrane according to claim 1, wherein: the step S1 includes:

s11, preparing a mask;

3. The microporous membrane forming and manufacturing method according to claim 2, wherein: in the step S11, the mask is manufactured by performing photolithography according to the hole diameters, the number and the arrangement of the through holes required by the microporous membrane.

4. The microporous membrane forming and manufacturing method according to claim 2, wherein: in the step S12, the substrate is treated with the TI-Primer reagent, and then the positive photoresist is coated.

5. The method for producing a microporous membrane according to claim 4, wherein: the substrate was spin coated with TI-Primer reagent at 2000 to 4000rpm for 18 to 22 seconds and then baked for fusion.

6. The microporous membrane forming and manufacturing method according to claim 2, wherein: in step S12, the substrate coated with the positive photoresist is baked at 120 to 135 ℃ for 10min using an oven or placed on a hot plate for 2min at 115 to 125 ℃.

7. The microporous membrane forming and manufacturing method according to claim 2, wherein: in the step S12, the positive photoresist is applied to a thickness of 18 to 22 μm.

8. The method for forming and manufacturing the microporous membrane according to claim 1, wherein: in step S2, the soft material is PDMS, the microporous membrane mold is a concave pattern structure, and the replication template is a convex pattern structure.

9. The method for producing a microporous membrane according to claim 1, which comprisesIs characterized in that: in the step S5, the intensity of the ultraviolet light is 5 to 13mW/cm ² The exposure time was 20 to 15 seconds.

10. The method for forming and manufacturing the microporous membrane according to claim 1, wherein: in the step S4, the pressure in the high-pressure environment is 0.2Mpa to 0.4Mpa.