A high-throughput concentration gradient droplet generation microfluidic chip based on fluid dispensing-recombination-micromixing

Abstract

The utility model discloses a kind of high-throughput concentration gradient droplet generation microfluidic chips based on fluid distribution-reorganization-micro mixing, it is related to microfluidic technical field, it includes glass substrate and the PDMS microchannel structure of being located above glass substrate, PDMS microchannel structure includes outer phase entrance and inner phase entrance, outer phase entrance is communicated with annular distribution channel by first radial channel, annular distribution channel inside is communicated with multiple concentration gradient droplet generation microchannels;Inner phase entrance is located in the center of the annular distribution channel, and it is communicated with each concentration gradient droplet generation microchannel by second radial channel and the one end of annular distribution channel and S type mixing channel far away, another end of S type mixing channel is connected outlet by third radial channel.The utility model is through the synergistic effect of extensible annular distribution channel, radial even distribution channel and S type mixing channel, realize the integration process of fluid distribution-reorganization-micro mixing, to generate multiple concentration gradient synchronously.

Description

Technical Field

[0001] This invention relates to a high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-recombination-micromixing, belonging to the field of microfluidic technology. Background Technology

[0002] Concentration gradients refer to the increasing or decreasing distribution of solute molecules within a specific region. They are a crucial element in analogical analysis of media of different concentrations and play a key role in drug screening, cell stimulation, immunoassay, protein crystallization, and nanomaterial synthesis. Effective concentration gradient control is fundamental to chemical and biochemical processes, and its flexible construction directly impacts the reliability and application potential of experimental results. For example, the size uniformity of nanoparticles is closely related to their concentration distribution during synthesis, and the efficiency of drug delivery systems depends on precise control of the concentration gradient of the delivery carrier.

[0003] Traditional methods of generating concentration gradients primarily involve manually preparing solutions of solutes at different concentrations. This not only consumes a large amount of reagents but also makes it difficult to generate concentration gradients with varying patterns of change as needed. This fails to meet the requirements for precise control at the cellular level and is ill-suited for high-throughput, high-precision experiments. Microfluidic technology, with its advantages of high efficiency, low consumption, and strong controllability, offers a new approach to the dynamic regulation of concentration gradients. However, existing microfluidic concentration gradient generation techniques still have significant limitations.

[0004] Microfluidic concentration gradients mainly include flow cytometry concentration gradient technology and concentration gradient microdroplet technology. Flow cytometry concentration gradient technology constructs a continuous flow system through multiple inlets and complex channel networks, using flow control to create a concentration gradient distribution in a specific region through convection and diffusion. Its classic implementation is a "Christmas tree-shaped" microfluidic chip, but this technology has limitations when used in cell experiments: fluid shear force affects cell growth, and the complex channel network occupies a large space. Higher-order tree-like networks, due to their numerous branching stages, require even higher space and driving pressure, and are prone to clogging or leakage.

[0005] Concentration gradient droplet technology utilizes microfluidic chips to generate sequences of microdroplets with specific concentration gradients. These monodisperse droplets serve as both microreactors and independent, mobile micro-experimental environments. Leveraging its picoliter to nanoliter sample processing capabilities and high-throughput manipulation characteristics, this technology has been widely applied in fields such as single-cell analysis, 3D cell culture, and drug screening.

[0006] Currently, there are two main methods for generating concentration gradient droplets: one is based on microfluidic chip structure design, which uses multi-stage split mixing to generate droplets with different concentration gradients. However, when generating more gradient distributions, a complex microchannel network is required and the gradient distribution is limited. The other method is to control the flow rate ratio of each fluid inlet so that the fluid is encapsulated into the droplet at a specific volume ratio and a concentration gradient is formed through internal diffusion and micro-mixing. This method has a relatively simple chip structure, but it is difficult to generate droplets with multiple concentration gradients simultaneously.

[0007] In summary, existing microfluidic concentration gradient generation technologies generally face challenges such as complex channel design, limited gradient modes, and limited mixing efficiency, making it difficult to meet the demand for flexible, high-throughput generation of multiple concentration gradients. Therefore, developing a microfluidic chip that combines high flexibility, rapid mixing, and simultaneous generation of multiple gradients has become one of the urgent challenges to be overcome in this field. Utility Model Content

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-reorganization-micromixing. Through the synergistic effect of scalable annular distribution channels, radial equalization channels and multiple S-shaped mixing channels, the fluid distribution-reorganization-micromixing integrated process is realized, thereby simultaneously generating multiple concentration gradients.

[0009] To achieve the above objectives, this utility model employs the following technical solution: This invention provides a high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-recombination-micromixing, including a glass substrate and a PDMS microchannel structure disposed on the glass substrate. The PDMS microchannel structure includes an outer phase inlet and an inner phase inlet. The outer phase inlet is connected to an annular distribution channel through a first radial channel. The annular distribution channel is connected to multiple concentration gradient droplet generation microchannels inside. The inner phase inlet is located at the center of the annular distribution channel, and it is connected to the end of each concentration gradient droplet generation microchannel away from the annular distribution channel and the end of the S-shaped mixing channel through a second radial channel. The other end of the S-shaped mixing channel is connected to the outlet through a third radial channel.

[0010] Furthermore, the number of the concentration gradient droplet generation microchannel, the second radial channel, the S-shaped mixing channel, and the third radial channel are in a one-to-one correspondence.

[0011] Furthermore, the concentration gradient droplet generation microchannel, the second radial channel, the S-shaped mixing channel, and the third radial channel are all eight in number.

[0012] Furthermore, the S-shaped mixing channel includes three inclined grooves arranged in sequence, which are connected by narrow channels to form an S-shape, and the surface of the inclined grooves is provided with groove structures for inducing fluid convection.

[0013] Furthermore, the inclined groove has a length of 3 mm, a width of 200 μm, and an inclination angle of 60°; the narrow channel has a length of 1.5 mm and a width of 114 μm.

[0014] Furthermore, the first radial channel has a length of 15 mm, a width of 200 μm, and a height of 76 μm; The radius of the annular distribution channel is 15mm, and its width is expandable; The length of the concentration gradient droplet generation microchannel is 5.4 mm; The second radial channel is L-shaped in general, and includes a vertical part and a bent part, wherein the length of the vertical part is 9.75mm; The second radial channel has a width of 200 μm and a height of 76 μm.

[0015] Furthermore, the width of the annular distribution channel is one of 200μm, 400μm, and 600μm.

[0016] Furthermore, the angle between the concentration gradient droplet generation microchannel and the annular distribution channel is 60°; the angle between the bend and the concentration gradient droplet generation microchannel is 60°.

[0017] Furthermore, the radii of the outer phase inlet and the inner phase inlet are 0.5 mm, the thickness of the glass substrate is 1 mm, and the thickness of the PDMS microchannel structure is 2 mm.

[0018] Compared with the prior art, the beneficial effects achieved by this utility model are as follows: This invention includes a glass substrate and a PDMS microchannel structure. Two fluids are injected through an external phase inlet and an internal phase inlet, respectively. The external fluid is divided into multiple branches in a specific ratio in an annular distribution channel, and the internal fluid is evenly distributed to each branch in a radial channel. The external and internal branches meet in an S-shaped connecting channel with inclined grooves. Chaotic convection is induced by the grooves to achieve efficient mixing and realize the rapid generation of gradients. The annular distribution channel of this invention adopts an expandable modular design, and the number of concentration gradients generated can be flexibly increased according to needs; by adjusting the width of the external annular channel, the concentration gradient can be adjusted, providing a platform for flexible control of the concentration gradient; This invention is applicable to fields such as drug screening, biosensing, nanoparticle synthesis, protein crystallization, 3D cell culture and analysis, and toxicity assessment, providing a new tool for chemical and biological analysis that relies on flexible concentration control. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a microfluidic chip for generating high-throughput concentration gradient droplets based on fluid distribution-recombination-micromixing in one embodiment of the present invention; Figure 2 This is a schematic diagram of the PDMS microchannel structure of a high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-recombination-micromixing in one embodiment of the present invention; Figure 3 This is a schematic diagram of the S-shaped mixing channel of a microfluidic chip for high-throughput concentration gradient droplet generation based on fluid distribution-recombination-micromixing in one embodiment of the present invention; In the figure: 1-glass substrate, 2-PDMS microchannel structure, 3-external phase inlet, 4-microchannel for generating concentration gradient droplets, 5-outlet, 6-internal phase inlet, 7-annular distribution channel, 8-S-shaped mixing channel, 801-sloping groove, 802-narrow channel, 9-first radial channel, 10-second radial channel, 11-third radial channel. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention. Example 1

[0021] like Figure 1 As shown, this embodiment of the invention provides a high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-recombination-micromixing, including a glass substrate 1 and a PDMS microchannel structure 2, wherein the PDMS microchannel structure 2 is disposed above the glass substrate 1. In this embodiment, the thickness of the glass substrate 1 is 1 mm, and the thickness of the PDMS microchannel structure 2 is 2 mm.

[0022] The PDMS microchannel structure 2 includes an outer phase inlet 3 and an inner phase inlet 6, both with a radius of 0.5 mm, for connecting to a Teflon tube.

[0023] The external phase inlet 3 is connected to the annular distribution channel 7 via a first radial channel 9. The first radial channel 9 has a length of 15 mm, a width of 200 μm, and a height of 76 μm. The annular distribution channel 7 has a radius of 15 mm, and its width is expandable. In this embodiment, the width of the annular distribution channel 7 can be flexibly expanded to one of 200 μm, 400 μm, and 600 μm as needed. The concentration gradient mode can be adjusted by adjusting the width of the annular distribution channel 7.

[0024] The annular distribution channel 7 is connected to multiple concentration gradient droplet generation microchannels 4. The concentration gradient droplet generation microchannels 4 are evenly distributed in the annular distribution channel 7, and the angle between the concentration gradient droplet generation microchannels 4 and the annular distribution channel 7 is 60°.

[0025] In this embodiment, the number of concentration gradient droplet generation microchannels 4 is 8. In this embodiment, the length of the concentration gradient droplet generation microchannels 4 is 5.4 mm.

[0026] The inner phase inlet 6 is located at the center of the annular distribution channel 7, and it is connected to the end of the microchannel 4 for generating droplets of each concentration gradient away from the annular distribution channel 7 through the second radial channel 10, and is also connected to one end of the S-shaped mixing channel 8.

[0027] In this embodiment, the second radial channel 10 is L-shaped, including a vertical section and a bent section. The length of the vertical section is 9.75 mm, and the overall width of the second radial channel 10 is 200 μm and the height is 76 μm. The angle between the bent section and the concentration gradient droplet generation microchannel 4 is 60°.

[0028] The S-shaped mixing channel 8 includes three inclined grooves 801, which are connected by narrow channels 802 to form an S-shaped structure. The inclined grooves 801 are 3 mm long, 200 μm wide, and have an inclination angle of 60°. The narrow channels 802 are 1.5 mm long and 114 μm wide. To induce fluid convection and improve mixing of the two fluid streams, the surface of the inclined grooves 801 is provided with a grooved structure.

[0029] The other end of the S-shaped mixing channel 8 is connected to the outlet through the third radial channel 11. Since there are 8 concentration gradient droplet generation microchannels 4 in this embodiment, the corresponding number of the second radial channel 10, the S-shaped mixing channel 8 and the third radial channel 11 are also 8. Example 2

[0030] Based on Example 1, this example also provides a fabrication method for a high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-recombination-micromixing, specifically including the following steps: (1) Select a 5cm×6cm glass substrate 1 and adopt a three-step cleaning process: ultrasonic cleaning with isopropanol (5min) → three-cycle rinsing with deionized water → purging with high-purity nitrogen. After visual inspection and approval, place it in an 85℃ oven to dry for 10 minutes.

[0031] (2) The mask pattern was designed using AutoCAD 2022. The first photolithography was performed using DuPont negative photoresist dry film (thickness 38μm) to obtain the main channel and the sub-channel mold. The film was then applied and aligned on the basis of the above mold. The groove structure on the S-shaped mixing channel 8 was constructed by the second exposure to form a complete mixing channel mold. The mold was then developed with 2% sodium carbonate solution, rinsed with deionized water and dried with nitrogen. It was then baked on a hot plate at 60℃ for 120s to strengthen the interface bonding force. The anti-sticking modification was performed by vapor deposition of trimethylchlorosilane (45μL) to form a monolayer coating.

[0032] (3) Mix PDMS prepolymer and curing agent at a mass ratio of 10:1, stir evenly and then pour into mold. Degas under vacuum for 30-40 minutes, and cure in an oven at 65°C for 3 hours. Use a punch (0.5-2 mm diameter) to punch holes at the outer phase inlet, inner phase inlet and 8 outlets of the PDMS layer for subsequent connection of Teflon tubes.

[0033] (4) The PDMS structure was bonded to the glass substrate (5 cm × 6 cm) by plasma bonding technology (hot pressing at 120℃ for 2 hours) to form an irreversible covalent bonding interface.

[0034] (5) Insert a Teflon plastic tube with an outer diameter of 1.32 mm into the inlet and outlet holes and fix and seal it with AB glue to obtain a high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-recombination-micromixing. Example 3

[0035] Based on Example 1, this example provides a microfluidic method for generating high-throughput concentration gradient droplets based on fluid distribution-recombination-micromixing, specifically including the following steps: (1) The high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-recombination-micromixing is placed in a plasma processing device, oxygen is introduced (20 s cm), and the treatment is carried out for 32 s to activate the surface, enhance hydrophilicity, and eliminate residual bubbles in the channel. If a hydrophobic surface is required, it can be injected with Aquapel glass antifogging agent and soaked for 2 minutes, cleaned with acetone, and dried at 80°C for 30 minutes.

[0036] (2) The external phase solution is the main fluid for generating the concentration gradient. It is prepared by mixing 15g of deionized water, 5g of anhydrous ethanol and 20g of brick red pigment (containing 50% sorbitol solution, 2.4% amaranth red and 1.88% glycerol).

[0037] (3) The inner phase solution is a fluid used to dilute the outer phase, prepared by mixing 30g of deionized water and 10g of anhydrous ethanol. In addition, to obtain a fluid with increased viscosity, 8g of glycerol (final concentration 20%) was added to both the inner and outer phase solutions for modification.

[0038] (4) Fix the high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-recombination-micromixing from step (1) onto the stage of a microscope (Olympus CKX53). Connect the external phase and internal phase reservoirs to the pressure pump (FluidicLab PC1) through Teflon tubes. Connect the high-speed camera (Olympus MTR3CMOS08300KPA) to the microscope for real-time acquisition of fluid mixing and concentration distribution images in the channel. Install ImageJ software on the computer for subsequent image grayscale analysis.

[0039] (5) Start the pressure pump, first introduce the inner phase solution to remove air from the channel, and ensure that the system is full of fluid. Simultaneously start the outer phase and inner phase pumps, and adjust the flow ratio (outer phase flow rate 0.5~7 mL / h, inner phase flow rate fixed at 7 mL / h or adjusted as needed). The outer phase is proportionally split through the annular channel (flow rate decreases sequentially from channel 1 to 8), and the inner phase is evenly split to each branch through the radial channel. The two fluids are efficiently mixed in the S-shaped mixing channel by the vortex induced by the groove, and finally a concentration gradient is formed at the 8 outlets.

[0040] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A microfluidic chip for high-throughput concentration gradient droplet generation based on fluid distribution-recombination-micromixing, characterized in that, The invention includes a glass substrate and a PDMS microchannel structure disposed on the glass substrate. The PDMS microchannel structure includes an external phase inlet and an internal phase inlet. The external phase inlet is connected to an annular distribution channel through a first radial channel. The annular distribution channel is connected to multiple concentration gradient droplet generation microchannels. The inner phase inlet is located at the center of the annular distribution channel, and it is connected to the end of each concentration gradient droplet generation microchannel away from the annular distribution channel and the end of the S-shaped mixing channel through a second radial channel. The other end of the S-shaped mixing channel is connected to the outlet through a third radial channel.

2. The high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-recombination-micromixing according to claim 1, characterized in that, The number of concentration gradient droplet generation microchannels, second radial channels, S-shaped mixing channels, and third radial channels corresponds one-to-one.

3. The high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-recombination-micromixing according to claim 2, characterized in that, The number of concentration gradient droplet generation microchannels, second radial channels, S-shaped mixing channels, and third radial channels are all 8.

4. The high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-recombination-micromixing according to claim 1, characterized in that, The S-shaped mixing channel includes three inclined grooves arranged in sequence, which are connected by narrow channels to form an S-shape. The surface of the inclined grooves is provided with groove structures for inducing fluid convection.

5. The high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-recombination-micromixing according to claim 4, characterized in that, The inclined groove is 3 mm long, 200 μm wide, and has an inclination angle of 60°; the narrow channel is 1.5 mm long and 114 μm wide.

6. The high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-recombination-micromixing according to claim 1, characterized in that, The first radial channel has a length of 15 mm, a width of 200 μm, and a height of 76 μm; The radius of the annular distribution channel is 15mm, and its width is expandable; The length of the concentration gradient droplet generation microchannel is 5.4 mm; The second radial channel is L-shaped in general, and includes a vertical part and a bent part, wherein the length of the vertical part is 9.75mm; The second radial channel has a width of 200 μm and a height of 76 μm.

7. The high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-recombination-micromixing according to claim 6, characterized in that, The width of the annular distribution channel is one of 200μm, 400μm, and 600μm.

8. The high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-recombination-micromixing according to claim 6, characterized in that, The angle between the concentration gradient droplet generation microchannel and the annular distribution channel is 60°; the angle between the bend and the concentration gradient droplet generation microchannel is 60°.

9. The high-throughput concentration gradient droplet generation microfluidic chip based on fluid distribution-recombination-micromixing according to claim 1, characterized in that, The radii of the outer phase inlet and the inner phase inlet are 0.5 mm, the thickness of the glass substrate is 1 mm, and the thickness of the PDMS microchannel structure is 2 mm.

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