A microfluidic chip microchannel remodeling method based on PDMS swelling

Abstract

The present application relates to the field of microfluidic chip microchannel modification and remodeling, and particularly relates to a microfluidic chip microchannel remodeling method based on PDMS swelling. The method comprises a pressure pump, which is connected with a liquid storage bottle through a gas pipeline, and provides necessary power to drive the flow of fluid. The liquid storage bottle is used for storing organic solvents. A flow controller controls the flow of the organic solvents in the liquid storage bottle through a fluid pipeline, and ensures that the fluid enters the microfluidic chip at a suitable flow rate. The present application is based on the porous characteristics and the permeability of PDMS material to organic solvents, and proposes a microfluidic chip microchannel remodeling method. Organic solvents (such as hexadecane and tetradecane) are injected into the microchannel, the organic solvents will penetrate the PDMS polymer network, and cause the swelling of PDMS, and then the microfluidic chip microchannel is remodeled, and finally the microfluidic chip with a special structure is constructed.

Description

Technical Field

[0001] This invention relates to the field of microchannel modification and reshaping of microfluidic chips, and in particular to a method for reshaping microchannels of microfluidic chips based on PDMS swelling. Background Technology

[0002] Microfluidic chips are a technology that uses a chip as an operating platform, is based on analytical chemistry, relies on microelectromechanical processing technology, and features a microchannel network as its structural characteristic. It is primarily applied in the life sciences. It manipulates fluids at the micrometer scale, forming a network of microchannels that allow controllable fluids to flow throughout the system, thereby enabling various functions in conventional chemistry, biology, materials science, optics, and other laboratories.

[0003] Existing microfluidic chip fabrication methods include excimer laser micromachining, femtosecond laser processing, solid-state laser (SLA) technology, fused deposition modeling (FDM), paper-based methods, microfilament molding, embedded sacrificial element methods, and PDMS curing-glass bonding methods. Among these, the PDMS curing-glass bonding method is widely used due to its simplicity, high processing precision, and low material cost. However, the microchannels of microfluidic chips fabricated using these methods are fixed, making deformation and reshaping difficult.

[0004] Furthermore, CN117984490A discloses a casting method for one-time molding of macro- and micro-structures of PDMS microfluidic chips. This method can rapidly manufacture PDMS microfluidic chips containing both micro and macro structures, precisely control the chip's planar shape and thickness, and can manufacture high-precision, high-density through-hole structures in one molding process. However, the geometry of the microchannels in the microfluidic chips prepared by this invention is fixed and cannot be changed according to requirements. CN117244599B discloses a method for fabricating PDMS microfluidic chips. First, a model including the microfluidic chip's inlet and outlet is fabricated on a substrate using paraffin wax. Then, PMDS is molded onto this model, allowing the PMDS to directly bond to the substrate. The paraffin wax model is then removed to obtain a complete microfluidic chip. This eliminates the need for a second bonding step between the top cover and the substrate, enabling the flexible fabrication of microfluidic chips of various shapes. However, for the microfluidic chip prepared by this invention, the geometry of its microchannels is also fixed and cannot be reshaped according to experimental requirements. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a microchannel reshaping method for microfluidic chips based on PDMS swelling. This invention designs a microchannel reshaping method for microfluidic chips, in which an organic solvent (e.g., hexadecane, tetradecane) is injected into the microchannel. The organic solvent permeates the PDMS polymer network, causing the PDMS to swell and reshape the microchannels of the microfluidic chip, ultimately constructing a microfluidic chip with an irregular structure.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] First aspect This invention provides a microchannel swelling and deformation device for microfluidic chips, comprising:

[0008] A pressure pump provides the necessary power to drive organic solvents into the microchannels of the microfluidic chip.

[0009] Storage bottles are used to store organic solvents (such as hexadecane and tetradecane).

[0010] A flow controller, connecting the liquid storage bottle and the microfluidic chip, is used to precisely control the flow rate of fluid flowing into the microfluidic chip.

[0011] Microfluidic chips are used to induce microfluidic flow, thereby enabling microfluidic experiments.

[0012] As a further implementation, the pressure pump is a vane pump, a positive displacement pump, or an electromagnetic pump.

[0013] As a further implementation, the liquid storage bottle is connected to the fluid inlet of the microfluidic chip.

[0014] As a further implementation, the flow controller can precisely control the flow rate of fluid flowing into the microfluidic chip.

[0015] As a further implementation, the organic solvent is a reagent capable of causing PDMS to swell, including but not limited to hexadecane and tetradecane.

[0016] Second aspect This invention provides a method for reshaping microchannels in microfluidic chips based on PDMS swelling, employing the microfluidic chip microchannel swelling and deformation device as described in the first aspect, and including the following steps:

[0017] Specifically, a pressure pump delivers high-pressure gas to a storage bottle and forces the organic solvent into a fluid hose. A flow controller regulates the flow rate of the organic solvent, ensuring it reaches the microfluidic chip at an appropriate rate. The microfluidic chip contains microchannels. Over time, the organic solvent in the microchannels gradually permeates into the PDMS wall material, inducing swelling of the PDMS. The microchannel has a rectangular cross-section with a large aspect ratio; therefore, the swelling on the sides is not significant, while more pronounced swelling and sedimentation occur at the top, achieving microchannel structural reshaping.

[0018] As a further implementation, after the organic solvent is injected into the microfluidic chip, the inlet of the microfluidic chip is sealed, thereby ensuring that the organic solvent fully penetrates the PDMS network.

[0019] As a further implementation, the pressure pump pressure is 0–100 kPa, and the flow controller flow rate adjustment range is 0–3000 μL / min.

[0020] The beneficial effects of the present invention are as follows:

[0021] Based on the porous properties and susceptibility of PDMS material to organic solvents, this invention proposes a method for reshaping microchannels in microfluidic chips. By injecting organic solvents (such as hexadecane or tetradecane) into the microchannels, the solvents penetrate the PDMS polymer network, causing the PDMS to swell and thus reshape the microchannels of the microfluidic chip, ultimately constructing a microfluidic chip with a unique structure. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 This is a schematic diagram of the microchannel swelling and deformation device for microfluidic chips in Embodiment 1 of the present invention.

[0024] Figure 2 These are schematic diagrams, physical images, and data analysis charts of the microchannels of a microfluidic chip before and after swelling.

[0025] Figure 3 This is a schematic diagram of the remodeled microchannel, showcasing three typical applications: rotating droplet mixers; high-throughput droplet digital PCR; and multiplex droplet 3D cell culture.

[0026] Figure 4 It adopts the method in Example 1 Figure 1The microfluidic chip constructed using this device is a rotating droplet mixer chip. Slight sedimentation occurs at the top of the microchannel, creating a non-uniform flow field and inducing droplet rotation. This chip is used for the efficient mixing of two-phase fluids within droplets.

[0027] Figure 5 It adopts the method in Example 1 Figure 1 The microfluidic chip constructed using the aforementioned device is a high-throughput droplet digital PCR chip. Drastic sedimentation at the top of the microchannel caused localized blockage in the outlet region, thus dividing the original outlet into two equal-sized secondary outlets. Therefore, this structure can simultaneously generate two droplets, doubling the droplet generation rate. This chip is used for high-throughput droplet digital PCR analysis.

[0028] Figure 6 It adopts the method in Example 1 Figure 1 The microfluidic chip constructed using the aforementioned device is a multi-volume droplet 3D cell culture chip. Drastic sedimentation at the top of the microchannel caused uneven blockage in the outlet region, thus dividing the original outlet into two secondary outlets of unequal sizes. Therefore, this structure can simultaneously generate two droplets of different sizes, achieving multi-volume droplet generation. This chip is applied to droplet-based 3D cell culture.

[0029] The diagram exaggerates the spacing or dimensions between parts to show their positions; the diagram is for illustrative purposes only.

[0030] The components include: 1. Pressure pump; 2. Gas pipeline; 3. Liquid storage bottle; 4. Organic solvent; 5. Gas pipeline; 6. Flow controller; 7. Microfluidic chip; 8. Microchannel. Detailed Implementation

[0031] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0032] Example 1

[0033] In a typical embodiment of the present invention, reference is made to... Figure 1 As shown, a microfluidic chip microchannel swelling and deformation device includes a pressure pump 1, a gas pipeline 2, a liquid storage bottle 3, an organic solvent 4, a fluid pipeline 5, a flow controller 6, and a microfluidic chip 7.

[0034] Pressure pump 1 is connected to liquid storage bottle 3 via gas line 2, providing the necessary power to drive the flow of fluid. Pressure pump 1 can be a vane pump, positive displacement pump, or electromagnetic pump to adapt to different fluid characteristics and pressure requirements.

[0035] The storage bottle 3 is used to store the organic solvent 4. The flow controller 6 controls the flow rate of the organic solvent 4 in the storage bottle 3 through the fluid pipeline 5, ensuring that the fluid enters the microfluidic chip 7 at a suitable flow rate.

[0036] The microfluidic chip 7 contains microchannels 8, the layout and size of which are determined according to specific experimental requirements.

[0037] The materials used for gas lines 3 and fluid lines 5 include glass, silicone, or plastic.

[0038] In this embodiment, a pressure pump 1 generates high-pressure gas, which is then delivered to a storage bottle 3 via a gas pipeline 2. This gas then forces the organic solvent 4 into a fluid hose 5, and finally into the microfluidic chip 7. A flow controller 6 regulates the flow rate of the organic solvent 4 within the microfluidic chip 7, ensuring that a suitable volume of organic solvent 4 is encapsulated within the microchannel 8. Over time, the organic solvent 4 gradually permeates into the PDMS walls of the microchannel 8, causing the PDMS to swell, macroscopically manifested as the expansion and deformation of the microchannel.

[0039] Based on the porous characteristics and susceptibility of PDMS material to organic solvents, this invention proposes a method for reshaping microchannels in microfluidic chips. An organic solvent 4 (e.g., hexadecane, tetradecane) is injected into the microchannel 8. The organic solvent 4 permeates the PDMS polymer network, causing the PDMS to swell, thereby reshaping the microchannel 8 of the microfluidic chip and ultimately constructing a microfluidic chip 7 with a heterogeneous structure.

[0040] The gas pressure in pressure pump 1 is 0 to 100 kPa, and a variety of preset pressure options are provided, such as 20 kPa, 50 kPa, 70 kPa, 80 kPa or 100 kPa, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable to meet different fluid pumping needs.

[0041] The pressure adjustment range of the flow controller 6 is 0 to 100 kPa, such as 20 kPa, 40 kPa, 60 kPa, 80 kPa or 100 kPa, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] Using the device described in this embodiment, the amount of top settlement deformation of the microchannel 8 is 2μm to 1000μm, such as 10μm, 50μm, 100μm or 800μm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] The flow rate range of organic solvent 4 is from 10 μl / min to 3000 μl / min, and includes 20 μl / min, 300 μl / min, 1500 μl / min or 2000 μl / min, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] The microchannels 8 contained in the microfluidic chip 7 are not limited to circular or rectangular shapes in cross-sectional design. The cross-section can include a variety of shapes to meet the personalized microfluidic experimental needs.

[0045] Figure 2 These are schematic diagrams and physical images of a microfluidic chip before and after microchannel swelling.

[0046] Figure 3 This is a schematic diagram of the remodeled microchannel, showcasing three typical applications: rotating droplet mixer, high-throughput droplet digital PCR, and multiplex droplet 3D cell culture.

[0047] Figure 4 This is a rotating microdroplet mixer chip. Slight sedimentation occurs at the top of the microchannel, creating a non-uniform flow field that induces microdroplet rotation. This chip is used for the efficient mixing of two-phase fluids within microdroplets.

[0048] Figure 5 This is a high-throughput droplet digital PCR chip. Drastic sedimentation at the top of the microchannel caused localized blockage in the outlet region, dividing the original outlet into two equal-sized secondary outlets. Therefore, this structure can simultaneously generate two droplets, doubling the droplet generation rate. This chip is used for high-throughput droplet digital PCR analysis.

[0049] Figure 6 This is a multi-volume microdroplet 3D cell culture chip. Drastic sedimentation at the top of the microchannel caused uneven blockage in the outlet region, dividing the original outlet into two secondary outlets of unequal sizes. Therefore, this structure can simultaneously generate two microdroplets of different sizes, i.e., multi-volume microdroplet generation. This chip is used in microdroplet 3D cell culture.

[0050] Example 2

[0051] This embodiment provides a microchannel reshaping method for microfluidic chips based on PDMS swelling, employing the microchannel swelling and deformation device described in Embodiment 1, and specifically including the following steps:

[0052] (1) Pressure pump 1 compresses external air and delivers it to storage bottle 3 through gas pipeline 2.

[0053] (2) The controller 6 adjusts the fluid flow rate and delivers the organic solvent 4 with a suitable flow rate to the microfluidic chip 7 through the fluid hose 5.

[0054] (3) The microfluidic chip 7 contains a microchannel 8, and the organic solvent is encapsulated in the microchannel 8 for 20 minutes. The organic solvent 4 gradually penetrates into the PDMS wall of the microchannel 8, causing the PDMS to swell, which is macroscopically manifested as the expansion and deformation of the microchannel 8.

[0055] (4) After the above-described transformation, the microfluidic chip 7 is transformed into a rotary micromixer chip, which is used for the efficient mixing of two-phase fluids inside microdroplets. Specifically, as follows... Figure 4 As shown in Figure a, fluorescent hydrogel and transparent hydrogel are injected into microchannel 8 through two aqueous inlets at the left end of microfluidic chip 7. The two hydrogels break down under the shearing action of the oil phase, forming Janus droplets. Due to the non-uniform flow field in the microchannel, the Janus droplets exhibit rotational behavior, thereby inducing efficient mass transfer between the two hydrogels and ultimately achieving efficient mixing. Figure 4 b shows the three-dimensional rotational behavior of Janus droplets in deformable microchannel 8. Figure 4 c shows the Janus droplet generation and rotating optical images under dark conditions. Figure 4 d shows the change in the mixing index, which increases with the increase of the distance traveled by the droplets. Figure 4 e shows the normalized fluorescence intensity of the droplets, which reaches 0.92 after the droplets have rotated, indicating excellent mixing efficiency. Figure 4 f shows the rotational state of the droplets at different locations, and it can be seen that rotational mixing is completed when the movement distance reaches 10 mm.

[0056] Example 3

[0057] This embodiment provides a microchannel reshaping method for microfluidic chips based on PDMS swelling. The difference from Embodiment 2 is that the encapsulation time of the organic solvent in microchannel 8 is significantly extended to 55 minutes. The organic solvent 4 gradually penetrates into the PDMS wall of microchannel 8, causing more severe swelling of the PDMS. Macroscopically, this manifests as blockage at the outlet of microchannel 8, thus dividing the original outlet into two secondary outlets of equal size.

[0058] After the above modifications, the microfluidic chip 7 was transformed into a high-throughput droplet digital PCR chip, which was applied to high-throughput droplet digital PCR analysis. Specifically, as follows... Figure 5As shown in Figure a, a PCR sample containing the target gene is injected into the microchannel 8 through the aqueous inlet at the left end of the microfluidic chip 7. It merges with the vertically flowing oil phase, and under the principle of laminar flow, both are transformed into a sheath flow, which flows collaboratively within the microchannel 8. When the sheath flow reaches the outlet of the microchannel 8, it splits into two droplets of the same size, thus forming a multiplicative droplet generation system. Figure 5 b shows an optical image of the droplet generation process. Figure 5 c shows the volume fraction of the internal phase fluid under different droplet generation hydrodynamic modes. Figure 5 d shows the change in the volume fraction of the internal phase fluid as a function of the internal phase fluid velocity. Figure 5 e illustrates the variation of droplet diameter with the internal phase fluid velocity. Figure 5 f demonstrates the stability of the droplet size. Figure 5 g shows the contrast in fluorescence intensity between positive and negative droplets. Figure 5 h shows PCR experiments at different sample concentrations. As the sample concentration increases, the number of positive droplets increases, and the experimental value matches the expected value to a high degree.

[0059] Example 4

[0060] This embodiment provides a microchannel reshaping method for microfluidic chips based on PDMS swelling. The difference from embodiments two and three is that the organic solvent is encapsulated in the microchannel 8 for 55 minutes, and uneven blockage occurs at the outlet of the microchannel 8, thereby dividing the original outlet into two secondary outlets of unequal size.

[0061] After the above modifications, the microfluidic chip 7 was transformed into a multi-volume microdroplet 3D cell culture chip, which is applied to microdroplet 3D cell culture. Specifically, as follows... Figure 6 As shown in Figure a, a PCR sample containing the target gene is injected into the microchannel 8 through the aqueous inlet at the left end of the microfluidic chip 7. It merges with the vertically flowing oil phase, and under the principle of laminar flow, both are transformed into a sheath flow, which flows collaboratively within the microchannel 8. When the sheath flow reaches the outlet of the microchannel 8, it splits into two droplets of different sizes, thus forming a multi-volume droplet generation system, enabling 3D culture of multi-volume cell clusters.

[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for reshaping microchannels in a microfluidic chip based on PDMS swelling, comprising a microfluidic chip microchannel swelling and deformation device, characterized in that, Includes the following steps: The pressure pump delivers high-pressure gas to the storage bottle and squeezes the organic solvent into the fluid hose. The flow controller is responsible for regulating the flow rate of the organic solvent to ensure that it reaches the microfluidic chip at the appropriate flow rate. Microfluidic chips have microchannels. Over time, organic solvents in the microchannels gradually penetrate into the PDMS wall material, thereby inducing PDMS swelling. The microchannel has a rectangular cross-section with a large aspect ratio. Therefore, the swelling on the sides is not high, while the top shows more obvious swelling and sedimentation, thus realizing the reshaping of the microchannel structure. The organic solvent was encapsulated in the microchannel for 20 minutes. The organic solvent gradually penetrated into the PDMS wall of the microchannel, causing the PDMS to swell, which was macroscopically manifested as the expansion and deformation of the microchannel. The microchannel swelling and deformation device for the microfluidic chip includes: A pressure pump provides the necessary power to drive organic solvents into the microchannels of the microfluidic chip; A storage bottle for storing an organic solvent; the organic solvent is a reagent that can cause PDMS to swell. A flow controller connects the liquid storage bottle and the microfluidic chip to precisely control the flow rate of fluid flowing into the microfluidic chip. After the organic solvent is injected, the inlet of the microfluidic chip is sealed to ensure that the organic solvent is encapsulated in the microchannel. Among them, the pressure of the pressure pump is 0 to 100 kPa, the flow rate adjustment range of the flow controller is 0 to 3000 μL / min, the flow rate range of the organic solvent is from 10 μl / min to 3000 μl / min, the top sedimentation deformation of the microchannel is 2 μm to 1000 μm, and its cross-sectional shape design includes a variety of shapes. Microfluidic chips are used to induce microfluidic flow, thereby enabling microfluidic experiments.

2. The microchannel reshaping method for microfluidic chips based on PDMS swelling according to claim 1, characterized in that, After the organic solvent is injected into the microfluidic chip, the inlet of the microfluidic chip is sealed to ensure that the organic solvent fully penetrates the PDMS network.

3. The microchannel reshaping method for microfluidic chips based on PDMS swelling according to claim 1, characterized in that, The liquid storage bottle is connected to the fluid inlet of the microfluidic chip.

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