Droplet microfluidic chip based on 3D printing

Abstract

The application relates to the technical field of micro-fluidic chips, and discloses a liquid drop micro-fluidic chip based on 3D printing, which comprises a continuous phase distribution unit, a spacing platform and a dispersed phase distribution unit, the continuous phase distribution unit, the spacing platform and the dispersed phase distribution unit are integrally formed through 3D printing and are sequentially stacked along the thickness direction of the chip. The continuous phase distribution unit comprises a continuous phase liquid inlet, a continuous phase liquid pool and a plurality of continuous phase channels which are connected from top to bottom. The dispersed phase distribution unit comprises a dispersed phase liquid inlet, a dispersed phase liquid pool and a plurality of dispersed phase channels which are connected from bottom to top. The continuous phase distribution unit, the dispersed phase distribution unit and the outer edge of the spacing platform form a semi-open shearing platform, the continuous phase solution flowing out of the continuous phase channel flows along the surface of the shearing platform to the four directions, generates shearing force on the dispersed phase solution, forms micro liquid drops on the shearing platform, and realizes the combination of high-throughput liquid drop generation and the stability of the chip structure.

Description

Technical Field

[0001] This invention relates to the field of microfluidic chip technology, and in particular to a droplet microfluidic chip based on 3D printing. Background Technology

[0002] With the deepening understanding of the concept of micrototal analysis systems, microfluidic chips have gradually moved from laboratory research to industrial applications, becoming an important research direction in modern science and technology. Their core advantage lies in their ability to achieve efficient analysis and manipulation using trace fluids as carriers, playing an irreplaceable role in point-of-care testing (POCT), genome sequencing, drug screening, and materials preparation. Currently, the global microfluidic product market continues to grow, placing higher demands on chip fabrication efficiency, structural complexity, and performance stability.

[0003] Early microfluidic chip fabrication relied on microelectromechanical systems (MEMS) processing technology. However, with evolving application demands, the limitations of this technology became increasingly apparent. It not only failed to meet the fabrication requirements of complex structures but also involved cumbersome and costly processes, making it unsuitable for small-batch customization and rapid iteration in R&D. Meanwhile, the rapid development of 3D printing technology, with the emergence of high-precision printing techniques such as stereolithography and digital light processing, broke through the technological bottlenecks in microfluidic chip fabrication, propelling it into a new phase of "rapid design, rapid fabrication, and rapid verification."

[0004] The deep integration of 3D printing technology and microfluidic chips not only solves many pain points of traditional processes but also expands the application boundaries of microfluidic chips. Related 3D-printed microfluidic chips all utilize T-shaped or step-T structures to form a complete shearing system, completing the microsphere shearing. The geometric features of the T-shaped structure include: a main channel to carry the continuous phase (such as oil or water phase), and side channels that connect orthogonally to the main channel to inject the dispersed phase. The two phases meet at the T-junction, forming a "T"-shaped layout, which greatly improves the overall uniformity of the chip.

[0005] However, in practice, it's crucial to consider not only the pipe diameter and the uniform distribution of liquid flow in the main pipeline, but also the spacing between channels. If the spacing is too small, it cannot withstand the internal pressure differential of the flowing liquid, and high-speed shearing of the liquid can easily cause penetration, rendering the chip unusable. Simultaneously, too small a spacing results in poor support between each layer of the chip, easily forming voids and causing chip printing failures. If the spacing is too large, it will occupy excessive internal space, drastically reducing the number of channels per unit volume. Therefore, actual production requires sacrificing some throughput to meet support requirements, making it impossible to achieve optimal performance in both high-throughput design and actual production. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a 3D-printed droplet microfluidic chip that achieves both high-throughput droplet generation and chip structure stability.

[0007] This invention provides a droplet microfluidic chip based on 3D printing, including a continuous phase distribution unit, a spacer platform, and a dispersed phase distribution unit. The continuous phase distribution unit, the spacer platform, and the dispersed phase distribution unit are integrally formed by 3D printing and are stacked sequentially along the thickness direction of the chip. The continuous phase distribution unit includes a continuous phase inlet, a continuous phase storage tank, and multiple continuous phase channels connected sequentially from top to bottom; The dispersed phase distribution unit includes a dispersed phase inlet, a dispersed phase storage tank, and multiple dispersed phase channels connected sequentially from bottom to top. A semi-open shearing platform is formed between the continuous phase distribution unit, the dispersed phase distribution unit, and the outer edge of the spacer platform. The continuous phase solution flowing out of the continuous phase channel flows outward along the surface of the shearing platform and generates shear force on the dispersed phase solution flowing out of the dispersed phase channel to form microdroplets on the shearing platform.

[0008] Optionally, the continuous phase distribution unit includes an upper disk, a dispersed phase channel that passes through the lower disk along the axial direction, the upper disk being fixedly connected to the spacer platform, and multiple continuous phase channels arranged in a circular array in the radial direction around the spacer platform. The dispersed phase distribution unit includes a lower disk, which forms multiple dispersed phase channels along its axial direction. The lower disk is fixedly connected to the spacer platform. The multiple dispersed phase channels are arranged in a circular array in the radial direction around the continuous phase channel. The upper disk and the lower disk have the same diameter. The upper disk, the spacer platform, and the lower disk form a semi-open shearing platform.

[0009] Optionally, the continuous phase inlet and the continuous phase storage tank are formed on the top disk, the top disk and the upper disk are integrally formed, and the diameter of the top disk is smaller than the diameter of the upper disk.

[0010] Optionally, both the dispersed phase inlet and the dispersed phase storage tank are formed on the lower disc.

[0011] Optionally, the continuous phase inlet is located at the top center of the top disk, and the dispersed phase inlet is located at the bottom center of the lower disk, with the continuous phase inlet and the dispersed phase inlet coaxially arranged.

[0012] Optionally, the continuous phase channel is tangent to the interval platform.

[0013] Optionally, the thickness of the spacer platform can range from 1mm to 5mm.

[0014] Optionally, the diameter of the continuous phase channel ranges from 2mm to 3mm, and the diameter of the dispersed phase channel ranges from 1mm to 2mm, with the diameter of the dispersed phase channel being smaller than that of the continuous phase channel.

[0015] Optionally, the diameter difference between the circles containing multiple continuous phase channels and the circles containing multiple dispersed phase channels is 2cm-3cm.

[0016] Optionally, the distance between the circular edge where the multiple dispersed phase channels are located and the edge of the lower disk is 1cm-1.5cm.

[0017] The technical solution provided by the embodiments of the present invention has the following advantages compared with the prior art: This invention provides a 3D-printed droplet microfluidic chip. A continuous phase distribution unit, a spacer platform, and a dispersed phase distribution unit are integrally formed using 3D printing technology and stacked sequentially along the chip thickness. The continuous and dispersed phase distribution units are each connected to multiple channels via their own independent reservoirs, forming a multi-layered three-dimensional flow distribution architecture. This allows for high-flow-rate uniform distribution of the continuous and dispersed phases within the chip. The spacer platform, acting as a partition between the continuous and dispersed phase distribution units, provides sufficient physical support to both layers, ensuring the quality of the 3D printing and the stability of the chip under high-pressure fluid conditions. Furthermore, its outer edge, together with the upper and lower distribution units, forms a semi-open shearing platform. This allows the continuous phase solution to freely diffuse outwards along the surface of the semi-open platform after flowing through multiple continuous phase channels. The shear force generated during this spreading process performs open shearing of the dispersed phase solution flowing out of the dispersed phase channels without channel constraints, thereby generating a large number of microdroplets without the need for traditional T-shaped or step-T-shaped shearing microchannels. Because there are no shearing channels, the overall throughput increases exponentially. A typical 10cm radius disc-type microfluidic chip has a throughput of around 60, but the 10cm radius disc-type microfluidic chip of this invention can reach around 400, which is 6-7 times that of a typical chip. Furthermore, this invention eliminates the need for channel shearing, significantly reducing the complexity of the microfluidic chip's shearing structure and lowering the likelihood of the entire chip becoming unusable due to blockage in a single channel. This invention fundamentally eliminates the contradiction between the spacing between the continuous phase transport channel and the dispersed phase transport channel and the chip structure support. The spacing between channels only needs to meet the basic structural support requirements without taking into account the precision constraints of the shearing channel. This avoids the technical problems in traditional closed microchannel structures, such as liquid high-pressure penetration or printing voids due to excessively small spacing, or a sharp reduction in the number of channels due to excessively large spacing encroaching on internal space. Thus, while ensuring chip manufacturability and structural reliability, it maximizes the release of internal chip space for arranging more fluid channels, achieving a balance between high-throughput droplet generation and chip structural stability. This significantly improves the droplet production efficiency per unit volume and reduces the risk of entire chips being scrapped due to local blockage. Attached Figure Description

[0018] To more clearly illustrate the embodiments and design schemes of the present invention, the accompanying drawings required for this embodiment will be briefly described below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the overall structure of a droplet microfluidic chip based on 3D printing provided in an embodiment of the present invention; Figure 2 A top view of a 3D-printed droplet microfluidic chip provided in an embodiment of the present invention; Figure 3 A cross-sectional view of a 3D-printed droplet microfluidic chip provided for an embodiment of the present invention; Figure 4 This is a front view of a droplet microfluidic chip based on 3D printing, provided as an embodiment of the present invention.

[0020] Explanation of reference numerals in the attached figures: 1. Continuous phase inlet; 2. Dispersed phase inlet; 3. Continuous phase reservoir; 4. Dispersed phase reservoir; 5. Continuous phase channel; 6. Dispersed phase channel; 7. Shearing platform; 8. Spacing platform; 9. Upper disc; 10. Lower disc; 11. Top disc. Detailed Implementation

[0021] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0022] The technical solutions provided by the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0023] First, this invention provides a 3D-printed droplet microfluidic chip, specifically as follows: Figure 1 and Figure 2 As shown, the chip includes a continuous phase distribution unit, a spacer platform 8, and a dispersed phase distribution unit. These three units are integrally formed by 3D printing and are stacked sequentially along the thickness direction of the chip. The continuous phase distribution unit includes a continuous phase inlet 1, a continuous phase reservoir 3, and multiple continuous phase channels 5, connected sequentially from top to bottom. The dispersed phase distribution unit includes a dispersed phase inlet 2, a dispersed phase reservoir 4, and multiple dispersed phase channels 6, connected sequentially from bottom to top. A semi-open shearing platform 7 is formed between the continuous phase distribution unit, the dispersed phase distribution unit, and the outer edge of the spacer platform 8. The continuous phase solution flowing out of the continuous phase channels 5 flows outwards along the surface of the shearing platform 7, generating shear force on the dispersed phase solution flowing out of the dispersed phase channels 6, thus forming microdroplets on the shearing platform 7.

[0024] This invention provides a 3D-printed droplet microfluidic chip. In use, the entire chip floats in a large cylindrical container filled with receiving liquid. A continuous phase solution, such as an oil phase, is injected into a continuous phase reservoir 3 through a continuous phase inlet 1. The continuous phase reservoir 3 serves as a pressure equalization and flow distribution chamber, ensuring pressure equalization and flow uniformity of the continuous phase solution before it enters multiple continuous phase channels 5. The continuous phase solution then flows out through multiple continuous phase channels 5 to the surface of a semi-open shearing platform 7 at the outer edge of a spacer platform 8. Simultaneously, a dispersed phase solution, such as an aqueous phase, is injected into a dispersed phase reservoir 4 through a dispersed phase inlet 2. After pressure is evenly distributed in the dispersed phase reservoir 4, the solution flows out through multiple dispersed phase channels 6 to the same shearing platform 7 surface.

[0025] Since the outlet of the continuous phase channel 5 is arranged around the periphery of the spacer platform 8, while the outlet of the dispersed phase channel 6 is located around the periphery of the continuous phase channel 5, the continuous phase solution spreads on the surface of the shear platform 7, forming a continuous flow layer that diffuses from the inside out. This flow layer generates a shear stress field along the platform surface during its outward movement. Due to the differences in viscosity and interfacial tension between the continuous phase solution and the dispersed phase solution, when the dispersed phase solution flows out of the dispersed phase channel 6 and contacts the surface of the shear platform 7, its liquid column or droplets are subjected to a viscous drag force from the outward-moving continuous phase flow layer. This drag force overcomes the surface tension and interfacial tension of the dispersed phase solution, causing the dispersed phase liquid column to neck and eventually break, forming uniformly sized microdroplets. Finally, as the continuous phase solution flows from around the shear platform 7 into the receiving liquid, the microdroplets accumulate and solidify at the bottom of the cylindrical container due to gravity.

[0026] Throughout the droplet generation process, the spacer platform 8 not only provides a supporting surface for the radial spread of the continuous phase solution, but also serves as an intermediate structural layer connecting the continuous phase distribution unit and the dispersed phase distribution unit, ensuring sufficient physical support strength between the two layers to prevent deformation or damage to the interlayer structure during high-pressure liquid injection. The semi-open design of the shearing platform 7 frees the droplet generation process from the size constraints of the closed microchannels. The spacing between the dispersed phase channels 6 and the continuous phase channels 5 only needs to meet the requirements of structural support and 3D printing, eliminating the need for precise channel gaps during the shearing process. This overcomes the strong coupling constraint between channel spacing and shearing efficiency in traditional T-shaped or step-T-shaped closed microchannel structures, enabling stable generation of high-throughput droplets.

[0027] refer to Figure 3The continuous phase distribution unit includes multiple upper disks 9, with continuous phase channels 5 penetrating the upper disks axially. The upper disks 9 are fixedly connected to the spacer platform 8, and the multiple continuous phase channels 5 are arranged in a radially arranged ring array around the spacer platform 8. The dispersed phase distribution unit includes a lower disk 10, with dispersed phase channels 6 penetrating the lower disk 10 axially. The lower disk 10 is fixedly connected to the spacer platform 8, and the multiple dispersed phase channels 6 are arranged in a radially arranged ring array around the continuous phase channels 5. The upper disks 9 and lower disks 10 have the same diameter; the upper disks 9, spacer platform 8, and lower disk 10 form a semi-open shearing platform 7.

[0028] With the above configuration, the upper disk 9 and the lower disk 10 are of equal diameter and are fixedly connected to the upper and lower sides of the spacer platform 8, respectively, forming a sandwich-like axisymmetric sandwich structure. This structure allows the chip to have a symmetrical mechanical distribution in the thickness direction. When high-pressure liquid is injected from both sides simultaneously, the expansion forces on the upper disk 9 and the lower disk 10 are balanced. The spacer platform 8 is located at the symmetrical center of the pressure on both sides, bearing only compressive stress rather than bending stress, thereby significantly improving the overall structural strength and pressure resistance of the chip and preventing the chip from delamination, deformation, or cracking under high-pressure (e.g., flow rate > 10 mL / min) operating conditions. At the same time, the equal diameter design makes the outer edges of the upper and lower disks flush in space, providing a regular geometric boundary for the shear platform 7, which is conducive to the formation of a uniform circumferential diffusion flow field after the continuous phase solution spreads, ensuring the consistency of shear force in all directions.

[0029] The continuous phase channels 5 are arranged in a ring array around the spacer platform 8. This allows the continuous phase solution, after exiting from multiple continuous phase channels 5, to form a radially diffused flow field uniformly distributed circumferentially on the surface of the shear platform 7. The continuous phase solution flowing out of each continuous phase channel 5 connects and merges with adjacent channels to form a complete annular flow layer, avoiding the problems of local flow field gaps or uneven flow velocity. This ensures that the shear force experienced by the dispersed phase solution at different circumferential positions is consistent, thereby ensuring the uniformity of the generated microdroplet size (CV value can be controlled within 5%). The dispersed phase channels 6 are also arranged in a ring array around the continuous phase channels 5, forming a concentric ring arrangement. This ensures that the distance and angle of the outlet position of each dispersed phase channel 6 relative to the continuous phase channel 5 are completely consistent. From a fluid dynamics perspective, this achieves parameter consistency for all droplet generation units, providing a structural basis for high-throughput (over 300 channels) parallel droplet generation. The concentric arrangement of the continuous phase channel 5 in the inner ring and the dispersed phase channel 6 in the outer ring ensures that the continuous phase solution, after flowing out from the inner ring, spreads radially from the inside to the outside along the surface of the shear platform 7. It inevitably passes through the outlet of the dispersed phase channel 6 along its flow path, thus applying shear force to the dispersed phase solution. This "inside-out shearing" arrangement fully utilizes the kinetic energy of the continuous phase solution during its spread, naturally forming a shear flow field without external driving. Simultaneously, the microdroplets generated by the dispersed phase channel 6 in the outer ring can be directly carried by the continuous phase to the chip edge after generation, without interfering with the continuous phase channel 5 in the inner ring, ensuring the continuity and stability of droplet generation.

[0030] The continuous phase channel 5 is formed by penetrating along the axial direction of the upper disk 9, and the dispersed phase channel 6 is formed by penetrating along the axial direction of the lower disk 10. This vertically oriented channel structure is consistent with the layer-by-layer deposition direction of 3D printing, allowing printing to be completed without additional support structures and reducing the printing failure rate. The upper disk 9, the spacer platform 8, and the lower disk 10 are fixedly connected, ensuring the alignment accuracy of the channels between each layer (alignment error can be controlled within ±0.1mm), avoiding problems such as channel misalignment and uneven flow distribution caused by assembly errors, and fully leveraging the technical advantages of integrated molding in 3D printing. The upper disk 9, the spacer platform 8, and the lower disk 10 together enclose a semi-open shearing platform 7. This structure integrates the three major functions of channel arrangement, fluid distribution, and droplet generation into the same spatial area, resulting in a compact structure and high space utilization. Compared to the traditional T-shaped chip approach that requires separate shearing channels, this invention integrates more channels within a limited disk area (approximately 400 channels can be integrated into a 10cm radius disk). At the same time, the semi-open structure facilitates observation and real-time monitoring of the droplet generation process, and also provides convenience for subsequent droplet collection and chip cleaning and maintenance.

[0031] Considering that if the upper disk 9 is too thick during the 3D printing process, under the condition of equal diameter, the edge of the upper disk 9 will droop, causing the outer edge of the channel to become smaller, causing the microspheres to accumulate at the outer edge and resulting in the microspheres breaking, in this embodiment, the continuous phase inlet 1 and the continuous phase storage tank 3 are formed on the top disk 11, the top disk 11 and the upper disk 9 are integrally formed, and the diameter of the top disk 11 is smaller than the diameter of the upper disk 9.

[0032] First, the continuous phase reservoir 3 is separated from the upper disk 9 and moved upwards to the smaller diameter top disk 11, allowing for a reduction in the thickness of the upper disk 9—requiring only a thickness sufficient to create the continuous phase channels 5. This prevents the outer edge of the upper disk 9 from sagging or warping under gravity during 3D printing due to excessive thickness and mass, ensuring the geometric accuracy and dimensional stability of the outer edge of the upper disk 9. It also maintains a regular outlet cross-sectional shape for the continuous phase channels 5, preventing increased local flow resistance due to deformation at the channel outlet, thus preventing microdroplets from accumulating, colliding, and breaking at the outer edge of the channels due to flow obstruction. Second, the diameter of the top disk 11 is smaller than that of the upper disk 9, allowing the top disk 11 to be spatially recessed within the upper surface of the upper disk 9. This does not encroach on the space available for the continuous phase channels 5 at the edge of the upper disk 9, ensuring that the number of channels that can be arranged per unit area remains unaffected. Furthermore, the top disk 11 and the upper disk 9 are integrally formed, eliminating the need for additional sealing connections between the reservoir 3 and the channel 5. This avoids the leakage risks and flow channel misalignment issues associated with multi-component assembly, ensuring the sealing and flow consistency of the continuous phase solution from the reservoir to each channel. In addition, the reduced diameter design of the top disk 11 makes its structure more compact, further reducing the overall weight of the upper distribution unit, mitigating the adverse effects of the 3D printing overhang structure on molding accuracy, and improving the printing success rate. In summary, this structural design, while ensuring high-throughput channel arrangement, balances the manufacturability of the 3D printing process with the functional reliability of chip droplet generation by thinning and lightweighting thick components and optimizing functional partitioning.

[0033] refer to Figure 4 Both the dispersed phase inlet 2 and the dispersed phase storage tank 4 are formed on the lower disc 10.

[0034] This invention integrates the dispersed phase inlet 2 and the dispersed phase reservoir 4 into the lower disk 10, achieving the following: First, this design integrates the dispersed phase inlet 2, the dispersed phase reservoir 4, and multiple dispersed phase channels 6 within the same lower disk 10, eliminating the need for additional connecting pipes or sealing structures. The dispersed phase solution enters the reservoir 4 through the inlet 2 and is directly distributed to each dispersed phase channel 6, minimizing the path and flow resistance. This ensures rapid and uniform distribution of the dispersed phase solution to each dispersed phase channel 6 during high-flow injection, avoiding pressure loss and flow deviation caused by pipe detours or connection interfaces. Second, compared to a solution where the dispersed phase reservoir 4 is a separate component assembled with the lower disk 10, this invention fully utilizes the axial space of the lower disk 10 to integrally form the reservoir chamber, reducing the overall number of chip components and interlayer interfaces. This reduces the assembly complexity of 3D printing, eliminates the risk of interlayer seal leakage, and improves the sealing reliability of the chip under high-pressure operating conditions. Secondly, the dispersed phase inlet 2 is located at the bottom of the lower disk 10, opposite to the upward direction of the outlet of the dispersed phase channel 6. This causes the dispersed phase solution to undergo a process in the storage tank 4 before turning into each dispersed phase channel 6. This turning process helps to further homogenize the pressure distribution in the storage tank 4, eliminate the jet effect at the inlet 2, and make the initial conditions of the fluid entering each dispersed phase channel 6 more consistent. This ensures that each droplet generation unit works synchronously and has a uniform particle size under the same operating conditions. In addition, the structure of the lower disk 10 integrating the storage tank increases the thickness of the lower part of the chip, forming a differentiated thickness distribution with the upper part after thinning via the top disk 11. During the 3D printing layer-by-layer curing process, the shrinkage stress of the upper and lower parts can be released asymmetrically, which helps to balance the internal stress distribution of the chip as a whole during the printing and curing process, reduce warping deformation, and improve the forming accuracy and structural stability of the chip.

[0035] Optionally, the continuous phase inlet 1 is located at the top center of the top disk 11, and the dispersed phase inlet 2 is located at the bottom center of the lower disk 10. The continuous phase inlet 1 and the dispersed phase inlet 2 are coaxially arranged.

[0036] First, the inlets are all located at the geometric center of their respective disks, so that when the continuous phase solution and the dispersed phase solution are injected into the continuous phase storage tank 3 and the dispersed phase storage tank 4 respectively, they can diffuse outward radially from the center point. This fully utilizes the circular symmetrical structure of the storage tanks to achieve natural pressure equalization and equal flow distribution of the fluids, ensuring that the inlet pressure of each continuous phase channel 5 or dispersed phase channel 6 in the circumferential direction is completely consistent. This fundamentally eliminates the problem of uneven flow caused by the offset of the inlet, where the flow rate is large in the near-end channel and small in the far-end channel. It ensures that all droplet generation units work synchronously under the same operating conditions, and the uniformity of the generated microdroplets is significantly improved (CV value can be controlled within 5%). Secondly, the continuous phase inlet 1 and the dispersed phase inlet 2 are coaxially arranged, resulting in a perfectly centered fluid input pattern along the central axis in the thickness direction of the chip. When the two phase solutions are injected simultaneously from both sides under high pressure, the forces along the central axis cancel each other out, resulting in overall chip stress balance. This avoids additional bending moments or torsional stresses inside the chip caused by inlet misalignment, thereby improving the structural stability and sealing reliability of the chip under high-pressure operating conditions. Thirdly, the coaxial layout facilitates connection between the chip and standard coaxial interfaces of external fluid drive systems (such as syringe pumps, pressure pumps, etc.), simplifying the chip installation and operation process and improving the chip's versatility and interchangeability with different drive devices. Furthermore, the centrally symmetrical arrangement of the inlets also makes the overall… The entire process of liquid inlet, diversion, and shearing for each chip unfolds around the same central axis. The flow channel layout is simple, symmetrical, and regular, which is conducive to setting boundary conditions and optimizing flow field design in CFD simulation, and reduces the design iteration cost in the chip development stage. At the same time, the upper and lower liquid inlets are coaxial and oriented in opposite directions (one up and one down), so that the two-phase fluids flow in the chip from top to bottom and from bottom to top respectively and converge in the spaced platform 8 region. When the two fluids meet at the shearing platform 7, they have a clear relative motion trend. The radial spread of the continuous phase solution along the platform surface and the axial outflow of the dispersed phase solution form an orthogonal or large-angle intersecting flow pattern in space, which provides favorable fluid dynamic conditions for efficient shearing and further improves the efficiency and stability of droplet generation.

[0037] Specifically, in this embodiment, the continuous phase channel 5 is tangent to the spacer platform 8, ensuring that all continuous phase solutions diffuse outward after flowing out of the continuous phase channel 5. If there is a certain distance between the continuous phase channel 5 and the spacer platform 8, the liquid will flow towards the spacer platform 8 after flowing out of the continuous phase channel 5, causing a difference in flow velocity and resulting in uneven microsphere size. This invention can avoid liquid shear instability and maximize the distance between the continuous phase channel 5 and the dispersed phase channel 6, thereby increasing the spheroidization rate.

[0038] The gap width of the shearing platform 7 is adjusted according to different requirements. The larger the gap, the larger the diameter of the sheared ball; the smaller the gap, the smaller the diameter of the sheared ball. However, it cannot be less than 1 mm, as this can easily cause the continuous phase solution to form a jet, making it impossible to stably shear the balls. If the gap is too large, it cannot guarantee that the flow rate of the dispersed phase solution can complete the shearing of the outer liquid. Therefore, in this embodiment of the invention, the thickness of the spacer platform 8 is in the range of 1 mm to 5 mm.

[0039] The function of the continuous phase channel 5 is to ensure that the continuous phase solution flows out uniformly from all sides of the continuous phase reservoir 3. The larger the aperture of the continuous phase channel 5, the lower the kinetic energy of the fluid; however, if it is too small, it is easy to form a jet, causing liquid splashing and affecting microsphere formation. The dispersed phase channel 6 is the main factor determining the microsphere size. If the dispersed phase channel is 1mm, the microsphere particle size will be around 1mm. The dispersed phase channel 6 is related to the spacer platform 8. The thickness of the spacer platform 8 is slightly larger than the diameter of the dispersed phase channel 6 because it is necessary to ensure sufficient space for the microspheres to flow after shearing. If the thickness of the spacer platform 8 is smaller than the diameter of the dispersed phase channel 6, the microspheres will be crushed in the liquid state. Therefore, in this embodiment of the invention, the diameter range of the continuous phase channel 5 is 2mm-3mm, the diameter range of the dispersed phase channel 6 is 1mm-2mm, and the diameter of the dispersed phase channel 6 is smaller than the diameter of the continuous phase channel 5. The slightly smaller diameter of the dispersed phase channel 6 ensures that the liquid can exit the channel in a microjet state.

[0040] If the continuous phase channel 5 and the dispersed phase channel 6 are too close, the liquid flowing out of the continuous phase channel 5 is not yet stable and is in an oscillating state, which is not conducive to microdroplet shearing. If they are too far apart, the disk diameter will increase, increasing the preparation cost. Based on this, in this embodiment of the invention, the diameter difference between the circle containing the multiple continuous phase channels 5 and the circle containing the multiple dispersed phase channels 6 is 2cm-3cm. 2cm-3cm can ensure stable liquid flow, shearing out uniform microdroplets, and effectively reduce costs.

[0041] Optionally, the distance between the circular edge of the multiple dispersed phase channels 6 and the edge of the lower disk 10 is 1cm-1.5cm. This ensures that after the microdroplets are sheared, there is sufficient channel length to allow the microdroplets to roll within the channels, improving sphericity. If the channels are too short, the droplets will roll too far, resulting in many irregularly shaped spheres, which will significantly affect product uniformity.

[0042] The above inventions are merely a few specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A droplet microfluidic chip based on 3D printing, characterized in that, It includes a continuous phase distribution unit, a spacer platform, and a dispersed phase distribution unit, which are integrally formed by 3D printing and are stacked sequentially along the thickness direction of the chip. The continuous phase distribution unit includes a continuous phase inlet, a continuous phase storage tank, and multiple continuous phase channels connected sequentially from top to bottom. The dispersed phase distribution unit includes a dispersed phase inlet, a dispersed phase storage tank, and multiple dispersed phase channels connected sequentially from bottom to top. The continuous phase distribution unit, the dispersed phase distribution unit, and the semi-open shearing platform formed between the continuous phase distribution unit and the outer edge of the spacer platform, the continuous phase solution flowing out of the continuous phase channel flows outward along the surface of the shearing platform and generates shear force on the dispersed phase solution flowing out of the dispersed phase channel to form microdroplets on the shearing platform.

2. The droplet microfluidic chip based on 3D printing as described in claim 1, characterized in that, The continuous phase distribution unit includes an upper disk, the continuous phase channel passes through the upper disk axially, the upper disk is fixedly connected to the spacer platform, and a plurality of the continuous phase channels are arranged in a circular array in the radial direction around the spacer platform. The dispersed phase distribution unit includes a lower disk, the dispersed phase channel extends through the lower disk axially, the lower disk is fixedly connected to the spacer platform, and a plurality of dispersed phase channels are arranged in a radially arranged ring array around the continuous phase channel. The upper disk and the lower disk have the same diameter; the upper disk, the spacer platform and the lower disk form a semi-open shearing platform.

3. The droplet microfluidic chip based on 3D printing as described in claim 2, characterized in that, The continuous phase inlet and the continuous phase storage tank are formed on the top disk, which is integrally formed with the upper disk, and the diameter of the top disk is smaller than the diameter of the upper disk.

4. A droplet microfluidic chip based on 3D printing as described in claim 3, characterized in that, Both the dispersed phase inlet and the dispersed phase storage tank are formed on the lower disk.

5. A droplet microfluidic chip based on 3D printing as described in claim 4, characterized in that, The continuous phase inlet is located at the top center of the top disk, and the dispersed phase inlet is located at the bottom center of the lower disk. The continuous phase inlet and the dispersed phase inlet are coaxially arranged.

6. A droplet microfluidic chip based on 3D printing as described in claim 1, characterized in that, The continuous phase channel is tangent to the interval platform.

7. A droplet microfluidic chip based on 3D printing as described in claim 1, characterized in that, The thickness of the spacer platform ranges from 1mm to 5mm.

8. A droplet microfluidic chip based on 3D printing as described in claim 1, characterized in that, The diameter of the continuous phase channel ranges from 2mm to 3mm, and the diameter of the dispersed phase channel ranges from 1mm to 2mm, with the diameter of the dispersed phase channel being smaller than that of the continuous phase channel.

9. A droplet microfluidic chip based on 3D printing as described in claim 1, characterized in that, The diameter difference between the circles containing the multiple continuous phase channels and the circles containing the multiple dispersed phase channels is 2cm-3cm.

10. A droplet microfluidic chip based on 3D printing as described in claim 1, characterized in that, The distance between the circular edge of the multiple dispersed phase channels and the edge of the lower disk is 1cm-1.5cm.

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