A fan-shaped microdroplet array generation device and method

Abstract

The application discloses a kind of fast programmable generation device and method of step droplet array, the device includes hydrophobic fan-shaped substrate, scraper, radial arrangement of hydrophilic stack point array and driving device.Mother droplet is moved along the surface of hydrophobic substrate by the rotary drive of scraper, and microdroplet is segmented into the microdroplet that resides in hydrophilic area using the surface tension difference between hydrophilic stack point and hydrophobic substrate;By adjusting the rotational speed of scraper or the diameter gradient distribution of stack point, the volume of droplet is dynamically controlled, and gradient droplet array is generated in single operation.The application does not need external pump valve or precision sealing device, has the advantages of open passive operation, low cost, high throughput and high stability, is suitable for drug screening, single cell analysis and instant detection etc.Situ, the flexibility and experimental efficiency of microdroplet generation are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of microfluidic chip technology, and in particular to a device and method for generating a fan-shaped microdroplet array. Background Technology

[0002] Microfluidic chip technology, a significant breakthrough in modern analytical science, enables high-throughput processing and reactions of biological samples through precise manipulation of microscale droplets, demonstrating significant advantages in areas such as drug screening, single-cell analysis, and point-of-care testing (POCT). Its miniaturized structure greatly reduces reagent consumption, closed-loop operation minimizes cross-contamination, and it is easily integrated with other detection modules, providing crucial technical support for precision medicine. However, traditional microfluidic chip systems have inherent limitations: droplet size and spatial distribution are fixed during the chip design phase, lacking dynamic adjustment capabilities. This rigid design necessitates the development of dedicated chips to address changes in experimental conditions, significantly increasing R&D costs and time, and severely restricting the technology's flexibility and application scope.

[0003] Existing improvement schemes attempt to enhance droplet control capabilities through two approaches:

[0004] 1. Continuous flow droplet preparation: This method relies on external pressure control equipment to drive the fluid. Although it can achieve dynamic adjustment of droplets, it has strict requirements for the sealing of the flow channel, and the equipment is complex and costly, making it difficult to meet the requirements for portability.

[0005] 2. Discrete digital droplet generation: Droplets are discretized and manipulated through electrodes or thermodynamic effects. Although this improves operational flexibility, it is difficult to achieve high throughput, low consumption and stable generation at the same time due to the physical mechanism. Moreover, the throughput is limited by the device structure.

[0006] The aforementioned solutions present inherent contradictions in key performance aspects such as dynamic adjustment, throughput, and equipment complexity. For example, continuous flow systems rely on precision pump and valve systems, making them unsuitable for open environments; discrete systems are limited by low throughput and high energy consumption, failing to meet large-scale screening requirements. Furthermore, existing technologies generally lack the ability to actively control droplet volume gradients, while gradient droplet arrays are valuable in scenarios such as drug dose response testing and cell heterogeneity research. Therefore, there is an urgent need for a novel microfluidic solution that is structurally simple, requires no complex peripherals, and can dynamically generate gradient droplet arrays to overcome existing technological bottlenecks and promote the wider application of this technology in precision medicine and high-throughput analysis. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a device and method for generating fan-shaped microdroplet arrays.

[0008] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0009] A fan-shaped microdroplet array generation device, characterized in that it includes: a hydrophobic fan-shaped substrate (1) for carrying mother droplets and guiding droplet flow;

[0010] The scraper (2) is positioned above the hydrophobic fan-shaped substrate (1) and does not directly contact the surface of the water-carrying fan-shaped substrate. It is used to drive the mother liquor droplets to move.

[0011] A radially arranged array of hydrophilic stack points (3) is distributed on the surface of the hydrophobic fan-shaped substrate (1), and the diameter and / or spacing varies in a gradient along the radial direction;

[0012] The drive unit (4) is connected to the scraper (2) and is used to control the scraper to rotate at a preset angular velocity;

[0013] When the mother droplet flows through the hydrophilic stack array (3) driven by the scraper (2), it is divided into a micro-droplet array with a volume gradient due to the difference in the hydrophilic and hydrophobic interfacial tension.

[0014] Preferably, the surface of the hydrophobic fan-shaped substrate (1) is modified with fluorosilane, and the liquid-solid contact angle is greater than 150° and the roll-off angle is less than 5°.

[0015] Preferably, the working surface edge of the scraper (2) has a cutting edge structure with a thickness of 0.1-1mm, and its material is selected from stainless steel, alumina, PDMS or fluorinated ethylene propylene copolymer, and the working surface is coated with fluorinated carbon coating.

[0016] Preferably, the hydrophilic stack array (3) is formed by selectively removing the substrate surface modification layer by a femtosecond laser, and the liquid-solid contact angle of each stack is 30° to 80°, and the diameter along the radial direction is distributed in an arithmetic or geometric sequence.

[0017] Preferably, the drive device (4) is a motor or spring, which controls the rotation speed of the scraper (2) to be 2-30 revolutions per minute.

[0018] The present invention also discloses a method for generating microdroplet arrays based on the above-mentioned device, comprising the following steps:

[0019] Step S1: Add the mother liquor to the surface of the hydrophobic fan-shaped substrate (1) to ensure that the volume of the droplet covers at least one hydrophilic stack point;

[0020] Step S2: Start the drive device (4) to make the scraper (2) rotate at a set angular velocity and drive the mother liquor droplets to move radially;

[0021] Step S3: When the mother liquid droplets flow through the hydrophilic stack array (3), micro-droplets are separated due to the interfacial tension difference between the hydrophilic stack and the hydrophobic substrate (1), and remain on the surface of each hydrophilic stack.

[0022] Step S4: By adjusting the angular velocity of the scraper (2) or the diameter distribution parameters of the hydrophilic stack, microdroplet arrays with different volume gradients are generated.

[0023] Furthermore, in step S4, the linear velocity of the scraper is changed by adjusting the rotation speed of the drive device (4) in real time, thereby achieving dynamic control of the droplet volume.

[0024] Compared with the prior art, the advantages of the present invention are as follows:

[0025] 1. Efficient generation of gradient droplet array: Through the synergistic effect of radially arranged hydrophilic stack points and hydrophobic fan-shaped substrate (1), combined with the directional drive of scraper, a microdroplet array with volume gradient can be generated in a single operation to meet the diverse needs of scenarios such as drug dose response testing and multi-concentration biochemical reactions.

[0026] 2. Dynamically controllable droplet volume adjustment: By adjusting the rotation speed of the drive device to change the linear velocity of the scraper, or by designing the diameter gradient distribution of the hydrophilic stack, the droplet volume can be controlled in real time and with precision. There is no need to redesign or replace the chip, which significantly improves the flexibility and efficiency of experiments.

[0027] 3. Open passive operation: The droplet generation process does not rely on external pumps, valves, electric fields or thermodynamic control equipment. It achieves spontaneous droplet separation only through the difference in hydrophilic and hydrophobic interfacial tension, which greatly reduces the complexity of the equipment and energy consumption. It is suitable for open environments and scenarios with strict requirements for equipment portability (such as POCT testing).

[0028] 4. Low cost and high compatibility: The solid surface hydrophilic and hydrophobic modification technology is mature and can be mass-produced; the hydrophobic substrate and scraper have a wide range of material choices (glass, PDMS, etc.), and are compatible with conventional microfluidic chip processing technology, significantly reducing production costs.

[0029] 5. High throughput and high stability: The radially distributed hydrophilic stacks allow the mother droplet to continuously generate multiple droplets in a single sweep, increasing the throughput several times over compared to traditional discrete droplet generation techniques. At the same time, droplet residence depends on the stable hydrophilic and hydrophobic properties of the substrate surface, avoiding droplet fusion or displacement and ensuring experimental reproducibility.

[0030] 6. Wide range of applications: The generated gradient droplet array can be directly used in biological experiments such as cell culture and drug screening, and can also be seamlessly integrated with analytical equipment such as microscopes and spectrometers, providing standardized microreaction units for multidimensional biochemical analysis. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the fan-shaped microdroplet array generation device according to an embodiment of the present invention;

[0032] Figure 2This is a schematic diagram illustrating the principle of droplet generation in an embodiment of the present invention;

[0033] Figure 3 This is a flowchart of the method for generating a fan-shaped microdroplet array according to an embodiment of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and examples.

[0035] like Figure 1 As shown, the present invention provides a fan-shaped microdroplet array generation device, including a hydrophobic fan-shaped substrate 1, a scraper 2, a hydrophilic stack point 3, and a motor drive device 4.

[0036] The hydrophobic fan-shaped substrate 1 should have a solid-liquid contact angle with the sample liquid greater than 90°. A dropper is used to add a sufficient volume of mother liquid droplets to the substrate to ensure that the droplet volume can completely cover the hydrophilic stack point 3 under external force.

[0037] The scraper 2: The scraper is fixed above the hydrophobic substrate by a bracket to ensure that there is a certain gap between the bottom of the working surface and the surface of the hydrophobic substrate.

[0038] The hydrophilic stack point 3 should have a solid-liquid contact angle with the sample liquid of less than 60°.

[0039] The driving device is a spring, a motor, or other device that can adjust the scraper speed.

[0040] like Figure 2 As shown, a hydrophilic region is prepared on the surface of a hydrophobic substrate, thereby altering the contact characteristics of the liquid on the substrate. When the liquid flows across the substrate surface under external force, the three-phase lines (water-liquid-gas) of the liquid change at the hydrophilic / hydrophobic interface, ultimately forming droplets in the hydrophilic region. Simultaneously, different driving velocities affect the effect of surface tension differences, resulting in different droplet volumes.

[0041] The droplet generation process of this invention is as follows (e.g.) Figure 3 ):

[0042] Step A: Using a dropper, add a sufficient volume of mother liquor droplet to the substrate, ensuring that the droplet volume, driven by external force, completely covers the hydrophilic stack point 3. Proceed to Step B;

[0043] Step B: The motor-driven scraper moves the mother liquor droplets, passing through the hydrophilic stack point 3. Proceed to Step C;

[0044] Step C: The difference in hydrophobic properties between the hydrophobic surface and the hydrophilic stack point 3 leads to a difference in surface tension between the droplets. This surface tension difference causes the mother droplet to separate into microdroplets that remain at the hydrophilic stack point 3. Then proceed to step D;

[0045] Step D: Since the hydrophilic stack points 3 are distributed radially, the linear velocity of the mother droplet varies when passing through hydrophilic stack points 3 with different radii of curvature. Different driving velocities affect the surface tension difference and capillary absorption time, resulting in different droplet volumes. Finally, a gradient droplet array of different volumes is generated in a single process. Proceed to Step E;

[0046] The volume of a microdroplet is determined by the following formula:

[0047] Where V is the droplet volume, σ is the liquid-gas surface tension, d is the diameter of the hydrophilic stack point, v is the scraper linear velocity, and k is a correction factor related to the solution properties.

[0048] Step E: By adjusting the angular velocity of the motor-driven scraper, the volume of the generated droplets can be easily and quickly controlled in real time.

[0049] The hydrophobic fan-shaped substrate 1 is made of glass with a nano-silica coating and fluorosilane modification to ensure that the liquid-solid contact angle is greater than 150° and the roll-off angle is less than 5°.

[0050] The scraper is characterized by a cutting edge structure with a working surface thickness of 0.1-1mm, and its length is greater than or equal to the radius of curvature of the fan-shaped hydrophobic substrate. The rigid material is made of stainless steel or alumina, and the flexible material is made of PDMS or fluorinated ethylene propylene copolymer. At the same time, the working surface is coated with a fluorinated carbon coating to ensure that the liquid does not adhere to the scraper surface and affect the preparation process.

[0051] The hydrophilic stack 3 utilizes femtosecond laser to selectively remove the surface modification layer, and the controllable laser direct writing changes the micro-nano structure at the stack to increase hydrophilicity, ensuring that the liquid-solid contact angle is controllable within the range of 30° to 80°.

[0052] The scraper 2 is fixed above the hydrophobic substrate using a bracket to ensure that the gap between the bottom of the working surface and the hydrophobic substrate is less than or equal to 0.1 mm.

[0053] The rotation speed of scraper 2 should be between 2 and 30 revolutions per minute to meet the droplet generation requirements under different experimental conditions.

[0054] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the implementation methods of the present invention, and should be understood that the scope of protection of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of the present invention.

Claims

1. A fan-shaped microdroplet array generation device, characterized in that, include: A hydrophobic fan-shaped substrate (1) is used to support the mother liquor droplets and guide the flow of the droplets; The scraper (2) is positioned above the hydrophobic fan-shaped substrate (1) and does not directly contact the surface of the water-carrying fan-shaped substrate (1) to drive the mother liquor droplets to move. A radially arranged array of hydrophilic stack points (3) is distributed on the surface of the hydrophobic fan-shaped substrate (1), and the diameter and / or spacing varies in a gradient along the radial direction; The drive unit (4) is connected to the scraper (2) and is used to control the scraper to rotate at a preset angular velocity; When the mother droplet flows through the hydrophilic stack array (3) driven by the scraper (2), it is divided into a micro-droplet array with a volume gradient due to the difference in the hydrophilic and hydrophobic interfacial tension.

2. The fan-shaped microdroplet array generation device according to claim 1, characterized in that: The surface of the hydrophobic fan-shaped substrate (1) is modified with fluorosilane, with a liquid-solid contact angle greater than 150° and a roll-off angle less than 5°.

3. The fan-shaped microdroplet array generation device according to claim 1, characterized in that: The working surface edge of the scraper (2) has a cutting edge structure with a thickness of 0.1-1mm. Its material is selected from stainless steel, alumina, PDMS or fluorinated ethylene propylene copolymer, and the working surface is coated with fluorinated carbon coating.

4. The fan-shaped microdroplet array generation device according to claim 1, characterized in that: The hydrophilic stack array (3) is formed by selectively removing the substrate surface modification layer by femtosecond laser. The liquid-solid contact angle of each stack is 30° to 80°, and the diameter along the radial direction is distributed in an arithmetic or geometric sequence.

5. The fan-shaped microdroplet array generation device according to claim 1, characterized in that: The drive device (4) is a motor or spring, which controls the rotation speed of the scraper (2) to be 2-30 revolutions per minute.

6. A method for generating a microdroplet array based on the device according to any one of claims 1 to 5, characterized in that, Includes the following steps: Step S1: Add the mother liquor to the surface of the hydrophobic fan-shaped substrate (1) to ensure that the volume of the droplet covers at least one hydrophilic stack point; Step S2: Start the drive device (4) to make the scraper (2) rotate at a set angular velocity and drive the mother liquor droplets to move radially; Step S3: When the mother liquid droplets flow through the hydrophilic stack array (3), micro-droplets are separated due to the interfacial tension difference between the hydrophilic stack and the hydrophobic fan-shaped substrate (1), and remain on the surface of each hydrophilic stack. Step S4: By adjusting the angular velocity of the scraper (2) or the diameter distribution parameters of the hydrophilic stack, microdroplet arrays with different volume gradients are generated.

7. The method for generating microdroplet arrays according to claim 6, characterized in that: In step S4, the linear velocity of the scraper is changed by adjusting the rotation speed of the drive device (4) in real time, thereby achieving dynamic control of the droplet volume.

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