Flexible film micro-channel chip as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of a flexible film micro-channel chip, and belongs to the technical field of micro-channels. The preparation method of the flexible film micro-channel chip provided by the invention comprises the following steps: by taking a first polydimethylsiloxane film as a base material, etching the base material by adopting an ultraviolet femtosecond laser processing method to obtain a base material containing a micro-channel structure; a second polydimethylsiloxane thin film is attached to the base material containing the micro-channel structure; and packaging the side surface of the laminating layer by using liquid polydimethylsiloxane to obtain the flexible thin film micro-channel chip. According to the preparation method disclosed by the invention, the problems of deformation, scorching or irregular edge of the micro-channel in the processing process are avoided.

Description

Technical Field

[0001] The present invention relates to the field of microfluidic technology, and more specifically to a method for preparing a flexible thin film microfluidic chip. Background Art

[0002] As an important part of micro-electro-mechanical systems (MEMS) and microfluidic systems, microfluidic technology is widely used in many fields such as biomedicine, chemical analysis, and environmental monitoring. With the development of these fields, the application demand for microfluidics is increasing, and the requirements for their structural accuracy, material compatibility, and processing technology are also gradually increasing. There are many methods for preparing microfluidics, the most common of which include photolithography, soft lithography, hot embossing, laser processing, and electrodeposition.

[0003] Photolithography is one of the most common methods for preparing microfluidic channels. It forms micron-scale patterns by coating, exposing and developing photosensitive materials, and then etching. Its process is complex, costly, and the materials are mainly used for silicon or glass. Soft lithography usually combines photolithography technology and uses elastomeric materials such as polydimethylsiloxane (PDMS) to replicate the micron-scale structure on the mold surface. Soft lithography relies on elastomeric molds (such as PDMS) for replication. Due to the limited mechanical strength of PDMS, the mold is easily worn or deformed during use, which affects the preparation accuracy, limited dimensional accuracy, and poor process repeatability. Hot embossing uses high temperature and high pressure to emboss the micron-scale structure on the mold onto the polymer material. Since the experiment requires high temperature and high pressure, the equipment cost is high, and the cooling and demolding process takes a long time. Electrodeposition forms microfluidic structures by selectively depositing metals or other materials on the substrate surface. Its process is complex, and it is difficult to control the uniform deposition, and it is limited by metal materials. With the continuous development of microfluidic technology, it is an urgent problem for current scientific researchers to develop a microfluidic processing method with simple process, high preparation efficiency, and applicable to a variety of materials.

[0004] In recent years, laser processing has gradually attracted attention in microfluidic preparation due to its high resolution, strong flexibility, and no need for masks. Laser processing is a precision processing method that uses a high-energy-density laser beam to directly engrave micron-scale structures on the surface of a material. This method is suitable for microfluidic preparation of various materials, especially in rapid prototyping and microfluidic preparation of heterogeneous materials.

[0005] Laser processing technology provides new solutions for the design and development of microfluidic systems to realize complex microfluidic structures and multifunctional integration. It can produce microfluidic systems with high precision, diverse materials, contactless processing, high efficiency, small amount or no post-processing, high repeatability, flexibility and suitable for complex three-dimensional microfluidic systems. Currently, CO2 lasers are often used in the commonly used laser etching microfluidic processing technology. CO2 laser direct writing processing technology has certain advantages in microfluidic manufacturing, such as high efficiency, contactless, and precision. However, the heat generated during CO2 laser processing can easily cause local melting or thermal damage of materials, especially when processing heat-sensitive materials such as polymers. This thermal effect may cause deformation, burning or irregular edges of microfluidic channels, thereby affecting the performance of microfluidic devices. Summary of the invention

[0006] In view of the above problems, the present invention provides a method for fine removal of microchannel structures by ultrafast laser in the ultraviolet band, which provides effective technical support for the preparation of chips for generating discrete microdroplets.

[0007] The first object of the present invention is to provide a method for preparing a flexible thin film microfluidic chip, comprising the following steps:

[0008] The first polydimethylsiloxane film is used as a base material, and an ultraviolet femtosecond laser processing method is adopted to etch the base material to obtain a base material containing a microchannel structure.

[0009] The second polydimethylsiloxane film is laminated on the base material containing the microfluidic structure; and the side of the laminated layer is then encapsulated with liquid polydimethylsiloxane to obtain a flexible film microfluidic chip.

[0010] In a preferred embodiment of the present invention, the wavelength of the laser beam of the laser processing process is 315nm to 400nm, for example, the wavelength of the laser beam is 315nm, 320nm, 340nm, 360nm, 380nm, 400nm, etc.

[0011] The laser pulse width is 50 fs to 10 ps, ​​for example, the laser pulse width is 50 fs, 100 fs, 1 ps, 10 ps, ​​etc.

[0012] The laser pulse frequency is 10 kHz to 100 kHz. For example, the laser pulse frequency is 10 kHz, 20 kHz, 30 kHz, 40 kHz, 50 kHz, 60 kHz, 70 kHz, 80 kHz, 90 kHz, 100 kHz, etc.

[0013] The beam scanning speed is 100mm / s~2000mm / s, and the beam scanning speed is 100mm / s, 500mm / s, 1000mm / s, 15000mm / s, 2000mm / s, etc.

[0014] The number of scans is 3 to 30 times, and the number of scans is 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, etc., but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0015] In a preferred embodiment of the present invention, the liquid polydimethylsiloxane is prepared by cross-linking and curing polydimethylsiloxane and a curing agent in a mass ratio of 5 to 8:1.

[0016] For example, in liquid polydimethylsiloxane, the mass ratio of polydimethylsiloxane to curing agent is 5:1, 6:1, 7:1, 8:1, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0017] In a preferred embodiment of the present invention, the first polydimethylsiloxane film is prepared by cross-linking and curing polydimethylsiloxane and a curing agent in a mass ratio of 5 to 10:1; the thickness of the first polydimethylsiloxane film is 0.1 mm to 3 mm.

[0018] In the first polydimethylsiloxane film, the mass ratio of polydimethylsiloxane to the curing agent is 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc.

[0019] The thickness of the first polydimethylsiloxane film is 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, etc., but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0020] In a preferred embodiment of the present invention, the second polydimethylsiloxane film is prepared by cross-linking and curing polydimethylsiloxane and a curing agent in a mass ratio of 8 to 15:1; the thickness of the second polydimethylsiloxane film is 0.1 mm to 1 mm.

[0021] In the second polydimethylsiloxane film, the mass ratio of polydimethylsiloxane to the curing agent is 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, etc.

[0022] The thickness of the second polydimethylsiloxane film is 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0023] In a preferred embodiment of the present invention, the microchannel opening width of the base material containing the microchannel structure is 10 μm to 1000 μm, for example, the microchannel opening width is 10 μm, 200 μm, 400 μm, 600 μm, 800 μm, 1000 μm, etc.

[0024] The depth is 10 μm to 1500 μm, for example, the depth is 10 μm, 100 μm, 300 μm, 600 μm, 900 μm, 1200 μm, 1500 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0025] In a preferred embodiment of the present invention, the microchannel cross section of the base material containing the microchannel structure is rectangular, V-shaped or trapezoidal.

[0026] The second object of the present invention is to provide a flexible thin film microfluidic chip prepared by the above preparation method.

[0027] The third object of the present invention is to provide the use of the above-mentioned flexible thin film microfluidic chip in preparing micro droplets.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The present invention utilizes ultraviolet femtosecond laser processing to process and prepare a substrate material containing a microfluidic structure. Since the femtosecond laser pulse duration is extremely short and there is almost no thermal influence, fine, smooth, and high-precision microstructure processing can be achieved, which is particularly suitable for the microfluidic production of heat-sensitive materials such as PDMS. The preparation method of the present invention avoids the problems of deformation, burning, or irregular edges of the microfluidic channel during the processing. The preparation method of the present invention can be applied to the processing of flexible film microfluidic chips made of various materials such as colorless transparent flexible films.

[0030] (2) According to the method of the present invention, personalized settings of microfluidic structures with different sizes, cross-sectional shapes, and path designs can be achieved to meet the needs of generating discrete droplets of different scales.

[0031] (3) The present invention uses liquid PDMS to encapsulate the microfluidic structure, successfully solving the problem of liquid leakage that occurs during the generation of discrete droplets. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the structure of the base material containing the microfluidic channel structure in Example 1.

[0033] Figure 2 This is a cross-sectional schematic diagram of the flexible thin film microfluidic chip in Example 2.

[0034] Figure 3This is a microscopic picture of the laser-processed microchannel on the surface of the flexible film in Example 1, where a is a three-dimensional structural morphology picture and b is a cross-sectional profile picture of A.

[0035] Figure 4 This is a microscopic image of the intersection area of ​​two mutually perpendicular microchannels laser-processed on the surface of the flexible film in Example 2, where a is a three-dimensional structural morphology image and b is a cross-sectional profile image of B.

[0036] Description of the drawings: 1-base material, 2-second PDMS film, 3-microchannel, 4-liquid reservoir, 5-first injection port, 6-second injection port, 7-liquid outlet. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] In order to achieve precise processing of the microchannel structure in the PDMS material, the present invention uses an ultraviolet femtosecond laser to perform graphic etching and micro-processing of the microchannel. Due to its extremely short pulse width and high energy density, the ultraviolet femtosecond laser can form high-precision microstructures on the surface and inside of the PDMS, reducing material damage caused by thermal effects.

[0039] Based on this, the present invention first uses CAD software to design the microchannel pattern required for the experiment and imports it into the laser processing system. The beam of the ultraviolet femtosecond laser is focused onto the surface of the PDMS material through a lens. The interaction between the laser beam and the PDMS material causes the nonlinear optical effect of the material, producing a high-precision etching effect. Under this high energy density, the PDMS material is quickly removed to form the required microchannel structure.

[0040] During laser processing, due to the ultra-short duration of femtosecond laser pulses, PDMS materials will not undergo significant thermal diffusion, thus minimizing the problem of thermal damage. At the same time, lasers in the ultraviolet band have higher photon energy and can finely process the micron and submicron structures of PDMS materials, making them suitable for complex microfluidic network design.

[0041] In addition, the depth and width of the microchannel can be precisely controlled by adjusting parameters such as laser power, pulse frequency and scanning speed. This non-contact processing method not only improves the processing accuracy of the microchannel, but also avoids the material deformation or damage problems that may occur in traditional micromachining technology.

[0042] To improve the mechanical strength and durability of the PDMS microfluidic channel, the microfluidic structure is usually encapsulated after processing. The encapsulation material selects another layer of PDMS to form a complete microfluidic chip. After encapsulation, the microfluidic channel can be used for biomedical analysis, chemical reactions or other microfluidic system applications.

[0043] It should be noted that the PDMS and curing agent used in the present invention were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. with the product number S466341.

[0044] Example 1

[0045] This embodiment provides a method for preparing a flexible thin film microfluidic chip, comprising the following steps:

[0046] Step 1, weigh PDMS and curing agent at a mass ratio of 8:1, mix them evenly, and cure them at room temperature for 2 hours to obtain a first PDMS film with a thickness of 2 mm, a length of 80 mm, and a width of 30 mm.

[0047] Step 2, using a UV femtosecond laser with a wavelength of 343nm, a laser pulse width of 209fs, a laser frequency of 100kHz, a beam scanning speed of 1500mm / s, adjusting the UV femtosecond laser power to 5W, and processing on the first PDMS film through 6 scans to obtain a matrix material containing a microfluidic structure; in this embodiment, the cross-section of the microchannel in the matrix material containing the microfluidic structure is an inverted trapezoid, the upper bottom width of the inverted trapezoidal microchannel is 300μm, the lower bottom width is 240μm, and the microchannel depth is 150μm.

[0048] Step 3: Weigh PDMS and curing agent at a mass ratio of 15:1, mix well, and cure at room temperature for 2 hours to obtain a second PDMS film with a thickness of 0.5 mm.

[0049] The second PDMS film is attached to the base material containing the microfluidic channel structure.

[0050] Step 4: Weigh PDMS and curing agent at a mass ratio of 5:1, and mix them evenly to obtain liquid polydimethylsiloxane.

[0051] Liquid polydimethylsiloxane was evenly applied to the sides of the substrate material containing the microfluidic structure and the second PDMS film bonding layer, and allowed to stand for 0.5 h at room temperature to solidify and form, thereby completing the encapsulation of the substrate material containing the microfluidic structure and the second PDMS film to obtain a flexible thin film microfluidic chip.

[0052] Example 2

[0053] This embodiment provides a method for preparing a flexible thin film microfluidic chip, comprising the following steps:

[0054] Step 1, weigh PDMS and curing agent at a mass ratio of 8:1, mix them evenly, and cure them at room temperature for 2 hours to obtain a first PDMS film with a thickness of 2 mm, a length of 80 mm, and a width of 30 mm.

[0055] Step 2, using a UV femtosecond laser with a wavelength of 343nm, a laser pulse width of 209fs, a laser frequency of 100kHz, a beam scanning speed of 1500mm / s, adjusting the UV femtosecond laser power to 5W, and processing on the first PDMS film through 15 scans to obtain a matrix material containing a microfluidic structure; in this embodiment, the cross-section of the microchannel in the matrix material containing the microfluidic structure is an inverted trapezoid, the lower bottom width of the inverted trapezoidal structure is 200μm, the upper bottom width is 350μm, and the microchannel depth is 400μm.

[0056] Step 3: Weigh PDMS and curing agent at a mass ratio of 15:1, mix well, and cure at room temperature for 2 hours to obtain a second PDMS film with a thickness of 0.5 mm.

[0057] The second PDMS film is attached to the base material containing the microfluidic channel structure.

[0058] Step 4: Weigh PDMS and curing agent at a mass ratio of 5:1, and mix them evenly to obtain liquid polydimethylsiloxane.

[0059] Liquid polydimethylsiloxane was evenly applied to the sides of the substrate material containing the microfluidic structure and the second PDMS film bonding layer, and allowed to stand for 0.5 h at room temperature to solidify and form, thereby completing the encapsulation of the substrate material containing the microfluidic structure and the second PDMS film to obtain a flexible thin film microfluidic chip.

[0060] Example 3

[0061] This embodiment provides a method for preparing a flexible thin film microfluidic chip, comprising the following steps:

[0062] Step 1, weigh PDMS and curing agent at a mass ratio of 5:1, mix them evenly, and cure them at room temperature for 2 hours to obtain a first PDMS film with a thickness of 0.1 mm, a length of 80 mm, and a width of 30 mm.

[0063] Step 2, using a UV femtosecond laser with a wavelength of 343nm, a laser pulse width of 209fs, a laser frequency of 100kHz, a beam scanning speed of 1500mm / s, adjusting the UV femtosecond laser power to 5W, and processing on the first PDMS film through 20 scans to obtain a matrix material containing a microfluidic structure; in this embodiment, the microchannel cross-section in the matrix material containing the microfluidic structure is V-shaped, the upper bottom width of the V-shaped microchannel is 10μm, and the microchannel depth is 20μm.

[0064] Step 3: Weigh PDMS and curing agent at a mass ratio of 8:1, mix well, and cure at room temperature for 2 h to obtain a second PDMS film with a thickness of 0.1 mm.

[0065] The second PDMS film is attached to the base material containing the microfluidic channel structure.

[0066] Step 4: Weigh PDMS and curing agent at a mass ratio of 5:1, and mix them evenly to obtain liquid polydimethylsiloxane.

[0067] Liquid polydimethylsiloxane was evenly applied to the sides of the substrate material containing the microfluidic structure and the second PDMS film bonding layer, and allowed to stand for 0.5 h at room temperature to solidify and form, thereby completing the encapsulation of the substrate material containing the microfluidic structure and the second PDMS film to obtain a flexible thin film microfluidic chip.

[0068] Embodiment 4,

[0069] This embodiment provides a method for preparing a flexible thin film microfluidic chip, comprising the following steps:

[0070] Step 1, weigh PDMS and curing agent at a mass ratio of 8:1, mix them evenly, and cure them at room temperature for 2 hours to obtain a first PDMS film with a thickness of 2 mm, a length of 80 mm, and a width of 30 mm.

[0071] Step 2, using a UV femtosecond laser with a wavelength of 343nm, a laser pulse width of 209fs, a laser frequency of 100kHz, a beam scanning speed of 1500mm / s, adjusting the UV femtosecond laser power to 5W, and processing on the first PDMS film through 20 scans to obtain a matrix material containing a microfluidic structure; in this embodiment, the microchannel cross-section in the matrix material containing the microfluidic structure is rectangular, the width of the rectangular microchannel is 1000μm, and the microchannel depth is 1500μm.

[0072] Step 3: Weigh PDMS and curing agent at a mass ratio of 15:1, mix well, and cure at room temperature for 2 hours to obtain a second PDMS film with a thickness of 0.5 mm.

[0073] The second PDMS film is attached to the base material containing the microfluidic channel structure.

[0074] Step 4: Weigh PDMS and curing agent at a mass ratio of 5:1, and mix them evenly to obtain liquid polydimethylsiloxane.

[0075] Liquid polydimethylsiloxane was evenly applied to the sides of the substrate material containing the microfluidic structure and the second PDMS film bonding layer, and allowed to stand for 0.5 h at room temperature to solidify and form, thereby completing the encapsulation of the substrate material containing the microfluidic structure and the second PDMS film to obtain a flexible thin film microfluidic chip.

[0076] The flexible thin film microfluidic chip prepared in Example 1 is as follows Figure 1 and Figure 2 As shown, the flexible thin film microfluidic chip includes a base material 1, a second PDMS film 2, a microchannel 3, a liquid reservoir 4, a first injection port 5, a second injection port 6 and a liquid outlet 7.

[0077] When preparing micro-droplets, the first injection port 5 and the second injection port 6 are connected to the external liquid inlet tube through a medical disposable intravenous infusion needle, and the liquid outlet 7 is directly connected to the liquid outlet tube; the external liquid inlet tube has an inner diameter of φ0.05~φ0.5mm and an outer diameter of φ0.5~φ2mm; the external liquid outlet tube has an inner diameter of φ0.1~φ1mm and an outer diameter of φ0.5~φ2mm. Driven by the driving pump, the discrete phase liquid enters from the second injection port 6, and the continuous phase liquid enters from the first injection port 5. The discrete phase liquid and the continuous phase liquid meet at the intersection. The discrete phase liquid continues to extend to form a "plug-shaped or "jet-shaped" liquid column, which is then pinched off by the shearing and squeezing of the continuous phase liquid and dispersed in the continuous phase liquid in the form of tiny volume units to form droplets, which flow into the liquid storage tank and then flow out through the liquid outlet 7. The A section of the flexible thin film microfluidic channel prepared by ultraviolet femtosecond laser in Example 1 was profile tested by confocal microscopy, as shown in FIG. Figure 3 As shown, it can be seen that the lower base width is about 240 μm, the upper base width is about 300 μm, the depth is about 150 μm, and the cross-sectional profile is an inverted trapezoidal structure.

[0078] The cross section B of the flexible thin film microfluidic chip prepared by ultraviolet laser in Example 2 was tested by confocal microscopy. Figure 4 As shown, it can be seen that the lower base width is about 200 μm, the upper base width is about 350 μm, and the depth is about 400 μm.

[0079] It can be seen that the present invention successfully realizes the processing of trapezoidal microfluidic channels on the PDMS substrate, the microfluidic channel structure is regular, and there is no obvious damage on the surface. The encapsulated microfluidic channel has good flow conductivity and is suitable for cell culture and analysis in biomedicine.

[0080] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0081] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a flexible thin film microfluidic chip, characterized in that: The following steps are involved: Using the first polydimethylsiloxane film as a base material, the base material is etched by an ultraviolet femtosecond laser processing method to obtain a base material containing a microchannel structure; The second polydimethylsiloxane film is laminated on the base material containing the microfluidic structure; and the side of the laminated layer is then encapsulated with liquid polydimethylsiloxane to obtain a flexible film microfluidic chip.

2. The method for preparing a flexible thin film microfluidic chip according to claim 1, characterized in that: The laser beam wavelength of the laser processing technology is 315nm~400nm, the laser pulse width is 50fs~10ps, the laser pulse frequency is 10kHz~100kHz, the beam scanning speed is 100mm / s~2000mm / s, and the number of scanning times is 3 times~30 times.

3. The method for preparing a flexible thin film microfluidic chip according to claim 1, characterized in that: The liquid polydimethylsiloxane is prepared by cross-linking and curing polydimethylsiloxane and a curing agent in a mass ratio of 5 to 8:

1.

4. The method for preparing a flexible thin film microfluidic chip according to claim 1, characterized in that: The first polydimethylsiloxane film is prepared by cross-linking and curing polydimethylsiloxane and a curing agent in a mass ratio of 5 to 10:1; the thickness of the first polydimethylsiloxane film is 0.1 mm to 3 mm.

5. The method for preparing a flexible thin film microfluidic chip according to claim 1, characterized in that: The second polydimethylsiloxane film is prepared by cross-linking and curing polydimethylsiloxane and a curing agent in a mass ratio of 8 to 15:1; the thickness of the second polydimethylsiloxane film is 0.1 mm to 1 mm.

6. The method for preparing a flexible thin film microfluidic chip according to claim 1, characterized in that: The microchannel opening width of the substrate material containing the microchannel structure is 10 μm to 1000 μm, and the depth is 10 μm to 1500 μm.

7. The method for preparing a flexible thin film microfluidic chip according to claim 1, characterized in that: The microfluidic channel cross section of the base material containing the microfluidic channel structure is rectangular, V-shaped or trapezoidal.

8. A flexible thin film microfluidic chip prepared according to the preparation method according to any one of claims 1 to 7.

9. Use of the flexible thin film microfluidic chip according to claim 7 in preparing microdroplets.

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