Method for manufacturing pdms film with pattern structure and application thereof

Abstract

The present disclosure provides a method for manufacturing a PDMS film with a pattern structure, comprising: S1, manufacturing a mold with a pattern structure, and performing surface silanization treatment on the mold; S2, spin coating a first PDMS mixture on the mold, and curing to obtain a PDMS film; S3, spin coating an electronic coating agent on the PDMS film, and drying to obtain an electronic coating agent film layer; S4, pouring a second PDMS mixture on the electronic coating agent film layer, and curing to obtain a blank PDMS layer; and S5, peeling off the sandwich structure of the PDMS layer-electronic coating agent film layer-PDMS film from the mold to obtain the PDMS film with the pattern structure. The present disclosure also provides an application of the PDMS film with the pattern structure. The manufacturing method can avoid damage caused by traditional direct peeling of the PDMS film, and increase the success rate of peeling of the PDMS film.

Description

Technical Field

[0001] This disclosure relates to the field of microfluidic chip technology, specifically to a method for fabricating and applying a PDMS thin film with a patterned structure. Background Technology

[0002] PDMS material is colorless and odorless, chemically stable, and possesses good light transmittance and excellent biocompatibility, making it widely used in the fabrication of microfluidic chips. PDMS films, in particular, can be used to create microvalves and micropumps. The traditional method for fabricating PDMS films involves coating PDMS onto a silanized mold, curing it, and then directly peeling it off. However, due to the thinness and low mechanical strength of the PDMS film, peeling requires overcoming van der Waals forces between the film and the mold, often resulting in deformation and structural damage. This method is time-consuming, labor-intensive, and has a low success rate. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address the aforementioned problems, this disclosure provides a method for fabricating and applying a PDMS film with a patterned structure, which at least partially solves the technical problems of deformation and structural damage that are easily caused during the peeling process of traditional PDMS films.

[0005] (II) Technical Solution

[0006] This disclosure provides a method for fabricating a PDMS film with a patterned structure, comprising: S1, fabricating a mold with a patterned structure and performing a surface silanization treatment on the mold; S2, spin-coating a first PDMS mixture onto the mold and curing it to obtain a PDMS film; S3, spin-coating an electronic coating agent onto the PDMS film and drying it to obtain an electronic coating agent film layer; S4, casting a second PDMS mixture onto the electronic coating agent film layer and curing it to obtain a blank PDMS layer; S5, peeling the sandwich structure of the blank PDMS layer-electronic coating agent film layer-PDMS film from the mold to obtain a PDMS film with a patterned structure.

[0007] Furthermore, in S3, the electronic coating agent is spin-coated onto the PDMS film at a rotation speed of 500–3000 rpm, a spin-coating time of 30 s–1 min, and a spin-coating number of times of 1–5.

[0008] Furthermore, the electronic coating agent in S3 includes: a polymer and a hydrofluoroether solvent; the polymer includes a fluorosilane polymer or a fluoroacrylic acid polymer, with a polymer mass fraction ranging from 0.1% to 2%.

[0009] Furthermore, the thickness of the PDMS film cured in S2 is less than 300 μm; the thickness of the electronic coating film obtained by drying in S3 is 10 nm to 10 μm; and the thickness of the blank PDMS layer obtained by curing in S4 is greater than or equal to 500 μm.

[0010] Furthermore, the first PDMS mixture in S2 includes PDMS and a curing agent, and the second PDMS mixture in S4 includes PDMS and a curing agent; wherein the mass concentration of PDMS in the first PDMS mixture is greater than the mass concentration of PDMS in the second PDMS mixture.

[0011] Furthermore, the mass ratio of polymer to curing agent in the first PDMS mixture ranges from 8:1 to 5:1; the mass ratio of polymer to curing agent in the second PDMS mixture ranges from 12:1 to 10:1.

[0012] Furthermore, after S5, the process includes: S6, stripping the blank PDMS layer; and S7, cleaning with an organic solvent to remove the electronic coating film.

[0013] Furthermore, the organic solvent includes one or more of acetone and isopropanol.

[0014] Furthermore, before S2 and S4, the process also includes: vacuum degassing the first PDMS mixture and the second PDMS mixture.

[0015] Another aspect of this disclosure provides the use of a patterned PDMS film obtained according to the aforementioned method for fabricating microvalves, micropumps, highly permeable and deformable film structures.

[0016] (III) Beneficial Effects

[0017] The method for fabricating and applying patterned PDMS films disclosed herein, by coating an electronic coating agent between two PDMS layers and directly casting the PDMS, ensures the flatness and integrity of the film, making it less prone to deformation. This avoids the damage caused by traditional direct peeling of PDMS films, increases the success rate of PDMS film peeling, and greatly reduces the operational difficulty of PDMS film fabrication. It can be used to fabricate structures such as microvalves, micropumps, highly permeable and deformable films, and has great application prospects in cell culture, drug screening, and single-cell analysis. Furthermore, the resulting sandwich structure of blank PDMS layer-electronic coating agent film-PDMS film can be directly bonded to glass, patterned or non-patterned PDMS, silicon wafers, etc., and then the blank PDMS and electronic coating agent film layers can be removed, increasing the stability and success rate of bonding patterned PDMS films with other materials. Attached Figure Description

[0018] Figure 1 The illustration shows a schematic flowchart of a method for fabricating a patterned PDMS film according to an embodiment of the present disclosure;

[0019] Figure 2 This schematically illustrates a fabrication flow chart of a sandwich structure of blank PDMS layer-electronic coating agent film layer-PDMS thin film according to an embodiment of the present disclosure;

[0020] Figure 3 A flowchart illustrating the PDMS film peeling and cleaning process according to an embodiment of the present disclosure is shown schematically.

[0021] Figure 4 A flowchart illustrating the bonding process between the sandwich structure and the glass according to an embodiment of the present disclosure is shown schematically.

[0022] Figure 5 This schematically illustrates a flowchart of the process of bonding the sandwich structure to the PDMS channel and then to the glass according to an embodiment of the present disclosure;

[0023] Figure 6 A flowchart illustrating the process of directly bonding a PDMS film to a PDMS channel according to an embodiment of the present disclosure is shown.

[0024] Figure 7 This schematically illustrates a flowchart of the process of bonding a PDMS film to glass and then to a PDMS channel according to an embodiment of the present disclosure.

[0025] Figure 8 A cross-sectional microscope image of a PDMS film directly bonded to a PDMS channel according to an embodiment of the present disclosure is shown schematically.

[0026] Figure 9 The illustration schematically shows a cross-sectional microscope image of a sandwich structure employing a blank PDMS layer-electronic coating film-PDMS thin film according to an embodiment of the present disclosure, with thick PDMS first bonded and then the blank PDMS removed. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0028] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0029] The various directional terms used in this disclosure, such as "front," "back," "left," "right," "up," and "down," are merely for the convenience of description and are used to describe the relative positional relationships between the components, not to limit this disclosure. Different product placement methods may lead to changes in the various directional descriptions.

[0030] To address the aforementioned issues, a blank PDMS film can be reversibly bonded to its surface to provide support and improve the peeling success rate. However, the blank PDMS film must be freshly fabricated and have a very clean and flat surface to adhere tightly to the PDMS film, which places high demands on the operation. Therefore, to meet the needs of microfluidic chip development, there is an urgent need to develop an easy-to-operate, fast, simple, and economical method for fabricating PDMS films.

[0031] The embodiments of this disclosure provide a method for fabricating a PDMS thin film with a patterned structure. Please refer to [link to relevant documentation]. Figure 1 The process includes: S1, fabricating a mold with a graphic structure and performing surface silanization treatment on the mold; S2, spin-coating a first PDMS mixture onto the mold and curing it to obtain a PDMS film; S3, spin-coating an electronic coating agent onto the PDMS film and drying it to obtain an electronic coating agent film layer; S4, casting a second PDMS mixture onto the electronic coating agent film layer and curing it to obtain a blank PDMS layer; S5, peeling the sandwich structure of the blank PDMS layer-electronic coating agent film layer-PDMS film from the mold to obtain a PDMS film with a graphic structure.

[0032] Figure 2 The flowchart of this fabrication method is shown. S1: First, a mold with a patterned structure, such as an SU8 mold, is fabricated on a silicon wafer. The mold surface is then silanized to reduce the van der Waals forces between the mold surface and PDMS, facilitating subsequent peeling. S2: A thin layer of PDMS is spin-coated and cured to obtain a PDMS film. S3: An electronic coating agent is spin-coated onto the PDMS surface and cured to obtain an electronic coating agent film layer. S4: A blank PDMS layer is then cast to obtain a blank PDMS layer. S5: The mold is demolded to obtain a PDMS film-coating-blank PDMS sandwich structure. This fabrication method, by coating an electronic coating agent between two PDMS layers and directly casting the PDMS, avoids the damage caused by traditional direct peeling of the PDMS film, increases the success rate of PDMS film peeling, and greatly reduces the operational difficulty of fabricating PDMS films.

[0033] Based on the above embodiments, S3, spin coating the electronic coating agent onto the PDMS film, includes: spin coating the electronic coating agent onto the PDMS film at a rotation speed of 500 to 3000 rpm, a spin coating time of 30 seconds to 1 minute, and a spin coating number of 1 to 5 times.

[0034] The electronic coating agent evaporates rapidly at room temperature, forming a corresponding polymer coating contained in its solvent on the PDMS film surface. This polymer coating, with a thickness ranging from 10 nm to 10 μm, covers the PDMS film and prevents cross-linking between the PDMS film and the blank PDMS. Directly casting blank PDMS onto the electronic coating surface creates a clean, smooth, bubble-free, and simple PDMS film-coating-blank PDMS sandwich structure. The interaction force between the coating and PDMS falls within the range of the interaction force between PDMS and the SU mold, and between the PDMS film and the blank PDMS. This ensures successful demolding while facilitating the peeling of the blank PDMS to obtain the PDMS film. Spin coating speeds within this range are beneficial for forming a smooth coating. Multiple spin coatings can also be used to obtain coatings of different thicknesses, further enhancing the ability to prevent cross-linking between the PDMS film and the blank PDMS, while also facilitating demolding and peeling of the PDMS film.

[0035] Based on the above embodiments, the electronic coating agent in S3 includes: a polymer and a hydrofluoroether solvent. The polymer can be a fluorosilane polymer or a fluoroacrylic acid polymer, and the polymer mass fraction ranges from 0.1% to 2%.

[0036] The functional components in electronic coating agents mainly include hydrofluoroether solvents and polymers. Hydrofluoroether solvents have low viscosity and are easily volatile, while the polymers exhibit low interaction with PDMS. The polymers, dissolved in the hydrofluoroether solvent, can be uniformly coated onto the PDMS film surface, forming a stable polymer coating at room temperature. This coating acts as a barrier against crosslinking between the PDMS film and the blank PDMS, facilitating the removal of the blank PDMS after demolding to obtain the final PDMS film. Specifically, examples include hydrofluoroether solvents containing 0.1% fluorosilane polymers or hydrofluoroether solvents containing 0.1%–2% fluoroacrylic acid polymers; alternatively, commercially available electronic coating agents, such as those from 3M, can be directly selected. TM Novec TM One or more stock solutions or diluents of 1720 Electronic Grade Coating (EGC-1720), 1702 Electronic Grade Coating (EGC-1702), and 1700 Electronic Grade Coating (EGC-1700).

[0037] Based on the above embodiments, the thickness of the PDMS film cured in S2 is less than 300 μm; the thickness of the electronic coating agent film obtained by drying in S3 is 10 nm to 10 μm; and the thickness of the blank PDMS layer obtained by curing in S4 is greater than or equal to 500 μm.

[0038] Typically, the thickness of the blank PDMS layer is greater than that of the PDMS film to provide stronger support. The electronic coating agent can achieve the corresponding function at the nanometer level. The thickness of the electronic coating agent is much smaller than that of the PDMS film and the blank PDMS layer. Together, the three form a sandwich-like structure.

[0039] Based on the above embodiments, the first PDMS mixture in S2 includes a polymer and a curing agent, and the second PDMS mixture in S4 includes a polymer and a curing agent; wherein, the mass concentration of the curing agent in the first PDMS mixture is greater than the mass concentration of the curing agent in the second PDMS mixture.

[0040] The composition of PDMS film and blank PDMS layer is similar, but the curing agent in PDMS film is usually higher. The cured PDMS film is more tough and less prone to cracking, which is beneficial for the subsequent peeling of blank PDMS layer.

[0041] Based on the above embodiments, the mass ratio of polymer to curing agent in the first PDMS mixture ranges from 8:1 to 5:1; the mass ratio of polymer to curing agent in the second PDMS mixture ranges from 12:1 to 10:1.

[0042] Based on the above embodiment, after S5, the method further includes: S6, peeling off the blank PDMS layer; S7, cleaning and removing the electronic coating agent film layer using an organic solvent.

[0043] The resulting sandwich structure of a blank PDMS layer-electron coating layer-PDMS thin film allows for direct removal of both the blank PDMS and electron coating layers, yielding a PDMS thin film with a patterned structure. Alternatively, it can be bonded to glass, patterned or unpatterned PDMS, silicon wafers, etc., before removing the blank PDMS and electron coating layers, increasing the stability and success rate of bonding the patterned PDMS thin film to other materials. The removal method for the blank PDMS and electron coating layers is simple and easy to operate; the blank PDMS is directly peeled off, and the electron coating layer can be removed by cleaning with acetone or isopropanol. This removal method does not affect the bonding of PDMS to materials such as glass or the fabrication of microfluidic chips with complex structures.

[0044] Based on the above embodiments, before S2 and S4, the method further includes: vacuum degassing the first PDMS mixture and the second PDMS mixture.

[0045] Before casting the PDMS mixture, it needs to be placed in a vacuum drying oven for preliminary degassing treatment to avoid introducing air bubbles and achieve uniformity control of the PDMS film.

[0046] This disclosure also provides the use of a patterned PDMS film obtained according to the aforementioned method for fabricating microvalves, micropumps, highly permeable and deformable film structures.

[0047] Compared with existing PDMS thin film fabrication methods, this disclosure allows for the direct casting of blank PDMS onto the non-patterned side of the PDMS thin film via spin-coating of an electronic coating agent. This ensures the flatness and integrity of the film, reduces deformation, and improves the success rate of film fabrication. After the sandwich structure of blank PDMS layer-electronic coating agent film-PDMS thin film is peeled off from the mold, the patterned side can be bonded to other PDMS sheets to form a composite structure. The blank PDMS can then be peeled off, improving bonding success and flatness. The electronic coating agent used can be easily removed with organic solvents, facilitating the bonding of the non-patterned side of the PDMS thin film to glass, silicon wafers, etc., enabling the fabrication of structures such as microvalves, micropumps, highly permeable and deformable films, with wide applications in cell culture, drug screening, and single-cell analysis.

[0048] The present disclosure will be further described below through specific embodiments. The following embodiments specifically illustrate the method for fabricating and applying the above-described patterned PDMS film. However, the following embodiments are merely illustrative of the present disclosure, and the scope of the disclosure is not limited thereto.

[0049] 1. PDMS film fabrication

[0050] like Figure 2 As shown, the SU8 mold was silanized to reduce the van der Waals forces between it and PDMS, facilitating demolding. The PDMS main agent and curing agent were mixed evenly at mass ratios of 5:1 and 10:1, respectively, and then degassed under vacuum. 10g of the 5:1 PDMS mixture was added dropwise to the mold on a balance. After degassed under vacuum, the mold was placed on a spin coater to spin-coate a PDMS film. After relaxation for 5 minutes, it was placed on a hot plate for curing. An electronic coating agent was then spin-coated, and after drying on the hot plate, a nano-coating was formed. Finally, 10g of the 10:1 PDMS mixture was poured, allowed to stand horizontally for 5 minutes, and then placed on a hot plate for curing. The sandwich structure of the blank PDMS layer, electronic coating agent film layer, and PDMS film could be successfully peeled off using a scalpel. Figure 3 As shown, the sandwich structure can be peeled off with a scalpel from the blank PDMS. The coating remaining on the PDMS film can be completely removed after cleaning with an organic solvent, resulting in a complete PDMS film with a patterned structure. If the PDMS film is peeled off directly, the pattern will be incomplete and deformed.

[0051] 2. PDMS thin film-glass chip

[0052] Using the blank PDMS layer-electro-coating agent film-PDMS thin film sandwich structure obtained in step 1, a PDMS thin film-glass chip is fabricated. For example... Figure 4 As shown, after perforation, the patterned surface can be directly bonded to the glass. The blank PDMS layer acts as a support during the bonding process, preventing deformation of the patterned structure on the PDMS film and improving the bonding success rate. Finally, the blank PDMS is peeled off to obtain the PDMS film-glass chip. Due to the permeability of PDMS, this PDMS film-glass chip can be used for single-cell culture.

[0053] 3. Channel PDMS-PDMS thin film-glass chip

[0054] Using the blank PDMS layer-electro-coating agent film-PDMS thin film sandwich structure obtained in step 1, a channel PDMS-PDMS thin film-glass chip was fabricated. Figure 5 As shown, the sandwich structure is bonded to the perforated PDMS channel structure to form a composite channel structure. The blank PDMS is then peeled off, and the electronic coating film is removed by cleaning. (As shown...) Figure 6 As shown, the PDMS film after peeling and cleaning can be bonded to the PDMS channel first, and then to the glass. If the PDMS film is directly peeled off and then bonded, it loses its support, and the channel is prone to collapse and deformation during the bonding process. Figure 7 As shown, if the thin film is bonded to the glass first and then to the channel PDMS, bubbles are prone to form when the PDMS thin film is directly bonded to the glass, which affects chip performance. Figure 8 A cross-sectional microscope image of the direct bonding of channel PDMS-thin PDMS is shown, revealing channel collapse and deformation. Figure 9 The image shows a cross-sectional microscope image of a sandwich structure consisting of a blank PDMS layer, an electronic coating layer, and a PDMS film, bonded to a thick PDMS film before the blank PDMS is removed. The PDMS film has a thickness of 110 μm and a cavity height of 50 μm. After bonding, the cavity is not deformed, and the bonding success rate is improved.

[0055] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A method for fabricating a PDMS thin film with a patterned structure, characterized in that, include: S1, fabricate a mold with a graphic structure, and perform surface silanization treatment on the mold; S2, spin-coating the first PDMS mixture onto the mold and curing it to obtain a PDMS film; S3, spin-coating the electronic coating agent onto the PDMS film and drying it to obtain an electronic coating agent film layer; the electronic coating agent comprises: a polymer and a hydrofluoroether solvent; the polymer comprises a fluorosilane polymer or a fluoroacrylic acid polymer, and the mass fraction of the polymer ranges from 0.1% to 2%; S4, the second PDMS mixture is poured onto the electronic coating agent film layer and cured to obtain a blank PDMS layer; the interaction force between the electronic coating agent film layer and the PDMS layer is within the range of the interaction force between the PDMS film and the mold and the interaction force between the PDMS film and the blank PDMS; S5, the sandwich structure of the blank PDMS layer-electronic coating agent film-PDMS film is peeled off from the mold to obtain a PDMS film with a patterned structure; wherein, the sandwich structure of the blank PDMS layer-electronic coating agent film-PDMS film can be directly bonded to glass, patterned or unpatterned PDMS, and silicon wafer, and then the blank PDMS layer and electronic coating agent film are removed, which increases the stability and success rate of bonding the patterned PDMS film with other materials.

2. The method for fabricating a PDMS thin film with a patterned structure according to claim 1, characterized in that, In step S3, spin-coating the electronic coating agent onto the PDMS film includes: The electronic coating agent is spin-coated onto the PDMS film at a speed of 500~3000 rpm, the spin-coating time is 30s~1min, and the number of spin-coating cycles is 1~5.

3. The method for fabricating a PDMS thin film with a patterned structure according to claim 1, characterized in that, The thickness of the PDMS film cured in S2 is less than 300 μm; The thickness of the electronic coating film obtained by drying in S3 is 10 nm to 10 μm. The thickness of the blank PDMS layer cured in S4 is greater than or equal to 500 μm.

4. The method for fabricating a PDMS thin film with a patterned structure according to claim 1, characterized in that, The first PDMS mixture in S2 includes a polymer and a curing agent, and the second PDMS mixture in S4 includes a polymer and a curing agent; The curing agent content in the first PDMS mixture is greater than the curing agent content in the second PDMS mixture.

5. The method for fabricating a patterned PDMS thin film according to claim 4, characterized in that, The mass ratio of polymer to curing agent in the first PDMS mixture ranges from 8:1 to 5:1; the mass ratio of polymer to curing agent in the second PDMS mixture ranges from 12:1 to 10:

1.

6. The method for fabricating a patterned PDMS thin film according to claim 1, characterized in that, Following S5, the following is also included: S6, peel off the blank PDMS layer; S7, Use an organic solvent to clean and remove the electronic coating film.

7. The method for fabricating a patterned PDMS thin film according to claim 6, characterized in that, The organic solvent includes one or more of acetone and isopropanol.

8. The method for fabricating a PDMS thin film with a patterned structure according to claim 1, characterized in that, Before steps S2 and S4, the process further includes: vacuum degassing the first PDMS mixture and the second PDMS mixture.

9. The PDMS film with a patterned structure obtained by the method of fabricating a PDMS film with a patterned structure according to any one of claims 1 to 8 is used for fabricating microvalves, micropumps, highly permeable and deformable film structures.

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