A multi-layer microfluidic coaxial extrusion printing nozzle and printing method

Abstract

The application discloses a kind of multilayer microfluid coaxial extrusion printing nozzle and printing method, to solve the problem of existing coaxial nozzle by lateral feed caused by coaxial eccentricity and long flow channel leads to cell damage big.The nozzle includes at least one outer layer flow channel module, outer layer flow channel module includes annular pressure stabilization chamber with side inlet;Fixed in annular pressure stabilization chamber inside, opposite side inlet setting flow column around, for symmetrically shunting incoming flow and guiding it to fill entire annular pressure stabilization chamber;And a tapered flow channel connected with annular pressure stabilization chamber outlet, its inner diameter gradually shrinks along extrusion direction and transitions into equal-diameter cylindrical outlet section at the end.The outer layer flow channel module of the application can effectively avoid high shear zone, significantly improve cell survival rate, and each module is stacked through sealing connection interface, so that coaxial nozzle with any number of layers can be freely constructed, with high coaxiality, high biocompatibility and strong modularity flexibility.

Description

Technical Field

[0001] This invention relates to the field of bio-additive manufacturing equipment technology, specifically to a multi-layer microfluidic coaxial extrusion printing nozzle and printing method for forming multi-layer concentric tubular structures. Background Technology

[0002] Bioprinting technology based on coaxial extrusion has irreplaceable advantages in manufacturing tubular structures such as blood vessels and nerve conduits. These applications require that the fluid layers of the extruded material maintain extremely high coaxiality. For example, the walls of natural microvessels are only a few micrometers to tens of micrometers thick. Any slight eccentricity during the extrusion process will lead to uneven wall thickness, or even weak points and ruptures, resulting in the loss of their biological function.

[0003] The fundamental reason for the eccentric flow of fluid at the outlet section of a multi-layer coaxial extrusion printhead is that the presence of the inner flow channel necessitates the use of a side inlet for material introduction into the outer flow channel. The laterally entering fluid carries significant lateral momentum, and if it flows directly to the outlet without sufficient rectification, the center point of its velocity and flow rate distribution will inevitably deviate from the geometric center of the printhead outlet.

[0004] To address this problem, two typical solutions exist in the existing technology. One solution involves setting up a sufficiently long, nested, straight annular flow channel with inner and outer tubes, attempting to fully consume the lateral momentum of the fluid through long-distance wall shearing, causing it to return to a constant axial flow before the outlet. A significant drawback of this solution is that the excessively long, narrow flow channel generates extremely high shear stress on the biomaterial, leading to the death of a large number of living cells mixed in the material, severely restricting the bioactivity of the printed structure. Simultaneously, the high flow resistance resulting from the long flow channel requires extremely high extrusion pressure and is highly susceptible to irreversible blockage.

[0005] Another approach is to use multiple symmetrically arranged lateral inlets, hoping that the lateral momentum carried by the symmetrically flowing fluids will cancel each other out at the center. While this approach is feasible in principle, in practical applications, it requires that the feed flow rate at each symmetrical inlet be kept highly consistent; otherwise, even a slight difference in flow rate will introduce new eccentricity. Furthermore, adding multiple inlets for each fluid layer will exponentially increase the complexity of the feed piping and extrusion control unit, significantly increasing the difficulty of system commissioning and maintenance.

[0006] Therefore, how to design a multilayer extrusion head that can achieve micron-level coaxiality with extremely low shear stress within an extremely short flow channel length, while also possessing modular flexibility, has become an urgent engineering problem to be solved. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multilayer microfluidic coaxial extrusion printing nozzle and printing method that can ensure both high coaxiality and maintain high cell activity.

[0008] To achieve the above objectives, the present invention provides a multilayer microfluidic coaxial extrusion printing nozzle, the nozzle comprising at least one outer flow channel module, the outer flow channel module comprising: an annular pressure stabilizing cavity having a side inlet; a flow-around column fixed inside the annular pressure stabilizing cavity and positioned opposite the side inlet, the flow-around column being used to symmetrically divert and guide the fluid flowing in from the side inlet to fill the annular pressure stabilizing cavity; and a tapering flow channel connected to the outlet of the annular pressure stabilizing cavity, the inner diameter of the tapering flow channel tapering along the fluid extrusion direction and transitioning at its end into a cylindrical outlet section of equal diameter.

[0009] As a preferred embodiment, the ratio of the radial inner diameter to the axial height of the annular flow channel space in the annular pressure-stabilizing cavity is greater than 2. This flat annular pressure-stabilizing cavity structure ensures that the fluid has sufficient circumferential space to develop and adjust its flow pattern, which is beneficial for the full dissipation of lateral momentum.

[0010] As a preferred embodiment, the flow-encircling column has a teardrop-shaped profile, consisting of a large arc-shaped end and two inwardly converging arc-shaped side surfaces. The flow-encircling column is positioned with the large arc-shaped end facing the side inlet. After the fluid enters from the side inlet, it impacts the large end face of the flow-encircling column, is divided into two equal streams (left and right), and flows along the arc-shaped side surfaces towards the rear of the flow-encircling column. The two streams smoothly merge at the end of the flow-encircling column and continue to fill the entire pressure-stabilizing chamber along a ring path. This teardrop-shaped flow-encircling column structure can achieve axisymmetric uniform distribution of fluid within a very short flow channel space.

[0011] As a preferred embodiment, the annular pressure-stabilizing cavity has upper and lower planar walls that are parallel to each other. When the fluid flows horizontally from one side to the symmetrical side in the pressure-stabilizing cavity, its lateral velocity component and the vortices formed by the historical flow are rapidly dissipated under the strong shearing action of the walls. This allows the fluid to quickly form a highly uniform annular peristaltic flow around the axis after entering the tapered flow channel, laying the foundation for the final micron-level coaxial extrusion.

[0012] As a preferred embodiment, the inner wall surfaces of the tapered flow channel and the cylindrical outlet section are continuous, smooth curved surfaces, without any sudden expansion or contraction of the flow channel cross-section or any sharp corners. This profile design minimizes the flow regions that cause high shear rates, ensuring extrusion flow rate while keeping the wall shear stress on the fluid at a low level. This helps maintain cell activity and significantly reduces the demand on the extruder's operating pressure.

[0013] As a preferred embodiment, the outer flow channel module is provided with sealed connection interfaces on the upper and lower end faces of the annular pressure stabilizing chamber, and adjacent modules are coaxially sealed together through these sealed connection interfaces. This modular design allows operators to freely assemble the required number of coaxial nozzles according to actual needs. In particular, this design also facilitates module cleaning and replacement for detachable module interfaces.

[0014] As a preferred option, the sealing connection interface is one of a sleeve-thread interface, a snap-fit ​​interface, a flange connection interface, or an interference fit interface; among them, the sleeve-thread interface achieves coaxial guidance and positioning through a high-precision cylindrical surface transition fit at the interface, and achieves reliable compression sealing by tightening the external thread, which is a particularly preferred option.

[0015] As a preferred embodiment, the end of the side inlet is equipped with a standardized leak-free quick-connect fitting to be compatible with conventional syringes or micro-feeding tubing. This standardized leak-free quick-connect fitting is preferably a Luer connector, ensuring one-time locking, self-sealing, and quick insertion and removal. Of course, other microfluidic connection devices with the same functions can also be used.

[0016] As a preferred embodiment, the nozzle further includes an inner nozzle module disposed on the central axis of the nozzle. The inner nozzle module has an inner inlet at the top, an inner tapered flow channel, and an inner cylindrical outlet section. At least one outer flow channel module is coaxially sleeved on the outside of the inner nozzle module. The inner flow does not require lateral pressure equalization. The inner nozzle module is sealed to the adjacent outer nozzle module via its lower sealing interface. The inner and outer materials meet at the final coaxial outlet, forming a coaxial core-shell structure and being extruded.

[0017] On the other hand, the present invention also proposes a method for bioprinting using the aforementioned multilayer microfluidic coaxial extrusion printing nozzle, which is characterized by including the following steps: S1: The outer layer printing material is injected into the annular pressure stabilizing cavity from the side inlet, so that the outer layer printing material impacts the flow column, and two branched material flows are obtained symmetrically split along both sides of the flow column; S2: The two split material streams flow circumferentially along the annular pressure stabilizing cavity and merge. The wall surface of the annular pressure stabilizing cavity is used to shear and dissipate the merged outer printing material to obtain an annular pressure stabilizing material stream with uniform circumferential velocity distribution. S3: Introduce the annular pressure-stabilizing material flow into the tapered channel, accelerate it along the tapered inner wall and transition it into axial flow, thereby obtaining a tapered extruded material flow with uniform axial velocity distribution. S4: Inject the inner layer printing material from the inner layer feed port of the inner layer nozzle module, so that the inner layer printing material flows through the inner layer tapered channel and the inner layer cylindrical outlet section in sequence to obtain the inner layer axial material flow. S5: The tapered extruded material flow and the inner layer axial material flow are merged at the end of the cylindrical outlet section, so that the tapered extruded material flow coaxially covers the outside of the inner layer axial material flow, thereby obtaining and extruding a coaxial core shell structure printed part.

[0018] Advantages of this invention: Compared with the prior art, the present invention has the following significant advantages: (1) The multilayer microfluidic coaxial extrusion printing nozzle provided by the present invention utilizes the synergistic effect of the teardrop-shaped flow column and the flat pressure stabilizing cavity within an extremely short rectification path to efficiently eliminate fluid eccentricity caused by lateral feeding, and achieve micron-level precise coaxiality at the outlet, thus providing a guarantee for manufacturing tubular structures with extremely high wall thickness precision.

[0019] (2) The present invention uses a tapered conical main flow path instead of a long horizontal DC channel, which avoids the fatal damage to cells caused by high shear stress and greatly reduces the driving pressure required for extrusion, effectively preventing tube blockage and making the printing process more stable and reliable.

[0020] (3) The modular structure of the present invention gives the equipment extremely high flexibility and economy. Users can freely configure it into a double-layer, triple-layer or more coaxial printhead, and can meet the diverse material combination printing needs without replacing the whole equipment. Attached Figure Description

[0021] Figure 1 This is an axial cross-sectional view of an embodiment of the dual-layer microfluidic coaxial extrusion printing nozzle proposed in this invention.

[0022] Figure 2 for Figure 1 The axial cross-sectional view of the inner module in the nozzle shown mainly illustrates the structural differences between the inner module and each outer module.

[0023] Figure 3 for Figure 1 The nozzle is shown in multiple views of a single outer module, including: a top sectional view along the AA direction, mainly showing the structure of the pressure stabilizing chamber and the flow column; a side sectional view along the BB direction, showing the location of the detachable sealed connection interface and the standardized quick-connect connector; and a perspective view of the outer module.

[0024] Figure 4 This is an axial cross-sectional view of an embodiment of the multilayer microfluidic coaxial extrusion printing nozzle proposed in this invention.

[0025] The meanings of the markings in the diagram are as follows: 10. Inner nozzle module; 11. Inner layer Luer feed inlet; 12. Sealed interface at the bottom of the inner module; 13. Inner conical flow channel; 14. Inner cylindrical outlet section; 20. Outer nozzle module; 21. Sealed interface on the outer module; 22. Pressure stabilizing chamber; 23. Flow column; 23a. The arc-shaped side of the flow column; 23b. Large end face of the flow column; 24. Sealed interface under the outer module; 25. Outer layer Luer side feed inlet; 26. Outer conical flow channel; 27. Outer cylindrical outlet section; 30. Final coaxial outlet. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0027] Example 1: like Figure 1 As shown in the figure, this embodiment demonstrates a dual-layer coaxial extrusion printing nozzle, which is assembled vertically and coaxially from an inner nozzle module 10 and an outer nozzle module 20.

[0028] like Figure 2 As shown, the inner nozzle module 10 is located on the central axis and adopts a top-through inner Luer inlet 11, which contains an inner conical flow channel 13 and an inner cylindrical outlet section 14. The inner layer flow does not require lateral pressure equalization. The inner nozzle module is sealed to other outer nozzle modules through a lower sealing interface 12. The inner and outer layer materials... Figure 1 The final coaxial outlet 30 shown meets, forming a coaxial core-shell structure and is extruded.

[0029] The outer nozzle module 20 adopts a side-feed method. It has an outer Luer-side feed port 25 on one side of its top, which connects to a flat, annular pressure-regulating chamber 22. (See attached image.) Figure 3 Sectional view BB and combined Figure 1 As shown, the ratio of the inner diameter (radial dimension) of the annular flow channel wall of the pressure stabilizing cavity 22 to its height (axial dimension) is preferably 5, ensuring that it has sufficient circumferential space to develop and adjust the flow pattern. In other embodiments, this ratio can be adjusted according to the specific printing material and accuracy requirements, but should be greater than 2 to ensure sufficient rectification effect.

[0030] like Figure 3 As shown in cross-sectional view AA, a teardrop-shaped flow-encircling column 23 is positioned inside the pressure-stabilizing chamber 22, directly opposite the outer Luer-side inlet 25. This flow-encircling column 23 consists of a large end face 23b facing the incoming flow and an arc-shaped side face 23a converging behind it. The radial length of the flow-encircling column 23 along the pressure-stabilizing chamber 22 is 0.9 times the radial width of the chamber. The lateral width of the projection of the large end face 23b onto the inlet plane of the side inlet 25 is equal to the diameter of the side inlet, and the minimum distance between the large end face 23b and the inner wall of the pressure-stabilizing chamber 22 is 0.1 times the radial width of the chamber. During printing, the biomaterial is injected through the inlet, impacts the large end face 23b, and is divided into two equal streams, left and right, flowing along the arc-shaped side face 23a towards the rear of the flow-encircling column 23. The two streams smoothly merge at the end of the flow-encircling column and continue to fill the entire pressure-stabilizing chamber 22 along a circular path. Throughout the circulation process, the fluid is constrained and sheared by the upper and lower walls of the pressure stabilizing chamber, and its radial velocity component is significantly attenuated, eventually forming a flow state with a uniform circumferential velocity distribution at the annular outlet of the pressure stabilizing chamber.

[0031] Subsequently, the fully uniformly pressed outer layer material enters the outer conical flow channel 26. For example... Figure 3 As shown in cross-sectional view BB, the inner diameter of the flow channel tapers gently from top to bottom, and the inner wall surface is a continuous smooth curved surface. The outer cylindrical outlet section 27 at the end of the flow channel maintains a constant diameter to further stabilize the extrusion expansion effect. This flow channel profile replaces the traditional long, narrow straight orifice, significantly shortening the material shearing process and greatly reducing the peak shear rate.

[0032] like Figure 1 and Figure 3As shown in the schematic diagram of the outer module, the pressure stabilizing chamber of the outer nozzle module 20 is provided with an upper sealing interface 21 and a lower sealing interface 24 at the lower end. Both the upper sealing interface 21 and the lower sealing interface 24 have high-precision cylindrical surfaces at their ends and threads at their middle and root. The two interfaces are matched with corresponding interfaces of other nozzle modules to form a detachable sealing connection interface. In this embodiment, the connection interface is specifically a sleeve-thread interface. The upper sealing interface 21 and the lower sealing interface 24 first achieve precise coaxial guidance and positioning through a high-precision cylindrical surface transition fit, and then are tightened by screwing on the external threads to ensure coaxiality and fluid sealing between the modules. However, it is understood that this detachable sealing connection interface is not limited to the sleeve-thread form. In alternative embodiments, a snap-fit ​​tightening structure, an interference fit structure, or a miniature flange bolt connection structure can also be used, as long as the requirements of coaxial positioning and fluid sealing are met. By locking and sealing the connection interface between the inner module 10 and one or more outer modules 20, a multi-layer coaxial nozzle can be quickly constructed, and any module can be easily disassembled, cleaned, or replaced.

[0033] All inlets are equipped with standardized, leak-free quick-connect fittings. In the illustrated embodiment, these quick-connect fittings are specifically standard Luer fittings (such as the inner Luer inlet 11 and the outer Luer side inlet 25) to ensure quick and sealed connection with external syringes or feed lines. Other types of miniature quick-connect fluid connectors may be selected based on actual flow rate and pipeline specifications without departing from the concept of this invention.

[0034] Example 2: like Figure 4 As shown, this embodiment demonstrates a multi-layer coaxial nozzle. Based on the first embodiment described above, by stacking one or more additional outer nozzle modules 20 between the already assembled inner module 10 and outer module 20, a three- or more-layer coaxial nozzle can be constructed. Specifically, each outer nozzle module 20 has a detachable sealed connection interface on its upper and lower end faces of the pressure stabilizing chamber, through which adjacent modules are coaxially sealed. Each outer nozzle module 20 has an independent side inlet and an independent teardrop-shaped flow column-flat pressure stabilizing chamber-conical flow channel rectification structure. The feeding and pressure equalization of each layer of fluid are independent and do not interfere with each other. The materials of each layer converge layer by layer at the final coaxial outlet 30, forming a concentric tubular structure with the required number of layers that is extruded.

[0035] It should be understood that in the above embodiments, the modules are detachably sealed and connected via a sleeve-thread interface, but this is not a limitation of the present invention. In alternative embodiments, in addition to detachable connections, the modules can also be permanently and non-detachably sealed and fixed by welding, bonding, or interference fit. Furthermore, products containing corresponding structural features can be integrally formed through additive manufacturing or other methods. All products possessing the same technical features, regardless of whether they are manufactured by separate assembly or integral forming, fall within the scope of the present invention. Example 3: The rectification process of the present invention will be further explained below in conjunction with the principles of fluid mechanics, so as to more clearly demonstrate the working mechanism of the present invention.

[0036] When the biomaterial (bio-ink containing living cells) is injected into the pressure-stabilizing chamber 22 at a certain flow rate through the outer Luer-side inlet 25, the fluid first impacts the large end face 23b of the teardrop-shaped flow column 23. Since the axial symmetry plane of the flow column 23 coincides with the side inlet axis, the incoming flow is precisely divided into two equal streams, left and right, by the large end face 23b. These two streams flow along the arc-shaped side surfaces 23a on both sides of the flow column 23 towards the rear of the flow column, and smoothly merge at the end of the flow column. This splitting-merging process disperses the lateral momentum originally concentrated in the side inlet direction into two symmetrical circumferential flow components.

[0037] Subsequently, the two converging fluids continue to flow along the annular path of the pressure-stabilizing chamber 22. The pressure-stabilizing chamber 22 has parallel upper and lower planar walls, and its radial dimension is much larger than its axial height (width-to-height ratio greater than 2), forming a flat annular flow channel. As the fluid flows from one side to the symmetrical side in this flat annular flow channel, its lateral velocity component is rapidly dissipated due to the strong shear constraint of the upper and lower planar walls, while the vortices formed by the historical flow also gradually decay under the shearing action of the walls. After sufficient rectification in this flat pressure-stabilizing chamber, the fluid has formed a highly uniform annular peristaltic flow pattern around the nozzle axis before entering the conical flow channel 26.

[0038] Finally, the fully pressurized fluid enters the outer conical flow channel 26. The inner diameter of this channel gradually narrows along the flow direction, and its inner wall is continuous and smooth, without any abrupt changes in cross-section or sharp corners. The fluid is gradually accelerated within the conical flow channel and transitions to axial flow, subsequently being stably extruded through the uniform-diameter cylindrical outlet section 27. Throughout the entire flow path, the wall shear stress experienced by the fluid remains at a low level, effectively protecting the living cells mixed into the material.

[0039] Example 4: This embodiment provides a method for bioprinting using the aforementioned multilayer microfluidic coaxial extrusion printhead.

[0040] First, the outer layer printing material is injected into the annular pressure stabilizing cavity 22 from the outer layer Luer side inlet 25. The outer layer printing material impacts the large end face 23b of the teardrop-shaped flow column 23 at a certain flow rate and is symmetrically split into two flow streams with equal flow rates on the left and right by the large end face 23b.

[0041] Next, the two split material streams flow along the arc-shaped sides 23a on both sides of the flow column 23 towards the rear of the flow column, smoothly merging at the end of the flow column and continuing to flow circumferentially along the annular path of the pressure stabilizing cavity 22. The merged outer layer printing material flows in a flat pressure stabilizing cavity with mutually parallel upper and lower planar walls. Its lateral velocity component is rapidly dissipated by the strong shear constraint of the wall surface, resulting in an annular pressure stabilizing material stream with a uniform circumferential velocity distribution.

[0042] Then, the annular pressure-stabilizing material flow is introduced into the outer conical flow channel 26, so that it is accelerated along the continuous smooth tapered inner wall surface and transitions to axial flow, thereby obtaining a conical extrusion material flow with uniform axial velocity distribution.

[0043] At the same time, the inner layer printing material is injected from the inner layer Luer inlet 11 at the top of the inner layer nozzle module 10, so that the inner layer printing material flows through the inner layer conical flow channel 13 and the inner layer cylindrical outlet section 14 in sequence to obtain the inner layer axial material flow.

[0044] Finally, the conical extrusion material flow and the inner layer axial material flow are merged at the final coaxial outlet 30, so that the conical extrusion material flow coaxially covers the outside of the inner layer axial material flow, forming a coaxial core shell structure printed part that is continuously extruded.

[0045] The above description is merely an embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related system fields, are similarly included within the scope of protection of the present invention.

Claims

1. A multilayer microfluidic coaxial extrusion printing nozzle, characterized in that, The nozzle includes at least one outer flow channel module (20), the outer flow channel module (20) comprising: An annular pressure regulating chamber (22) having a side inlet (25); A flow-around column (23) is fixed inside the annular pressure-stabilizing cavity (22) and positioned opposite the side inlet (25). The flow-around column (23) is used to symmetrically divert the fluid flowing in from the side inlet (25) and guide it to fill the annular pressure-stabilizing cavity (22). And a tapered flow channel (26) connected to the outlet of the annular pressure stabilizing chamber (22), the inner diameter of the tapered flow channel (26) tapering along the fluid extrusion direction and transitioning at its end to a cylindrical outlet section (27) of equal diameter.

2. The multilayer microfluidic coaxial extrusion printing nozzle according to claim 1, characterized in that, The ratio of the radial inner diameter of the annular flow channel space of the annular pressure stabilizing cavity (22) to its axial height is greater than 2.

3. The multilayer microfluidic coaxial extrusion printing nozzle according to claim 1, characterized in that, The flow-around column (23) has a teardrop-shaped profile and is composed of a large end arc surface (23b) and two inwardly converging arc-shaped side surfaces (23a). The flow-around column (23) is positioned with the large end arc surface (23b) facing the side inlet (25).

4. The multilayer microfluidic coaxial extrusion printing nozzle according to claim 1, characterized in that, The annular pressure stabilizing cavity (22) has an upper and lower planar walls that are parallel to each other.

5. The multilayer microfluidic coaxial extrusion printing nozzle according to claim 1, characterized in that, The inner wall surfaces of the tapering channel (26) and the cylindrical outlet section (27) are continuous smooth curved surfaces, and there is no sudden expansion or contraction of the channel cross-section.

6. The multilayer microfluidic coaxial extrusion printing nozzle according to claim 1, characterized in that, The outer flow channel module (20) is provided with sealing connection interfaces (21, 24) on the upper and lower end faces of the annular pressure stabilizing cavity (22), and adjacent modules are coaxially sealed and connected through the sealing connection interfaces (21, 24).

7. The multilayer microfluidic coaxial extrusion printing nozzle according to claim 6, characterized in that, The sealing connection interface (21, 24) is one of the following: sleeve-thread interface, snap-fit ​​interface, flange connection interface or interference fit interface.

8. The multilayer microfluidic coaxial extrusion printing nozzle according to claim 1, characterized in that, The nozzle also includes an inner nozzle module (10), which is disposed on the central axis of the nozzle. The inner nozzle module (10) has an inner inlet (11), an inner tapered flow channel (13), and an inner cylindrical outlet section (14) located at the top. At least one outer flow channel module (20) is coaxially sleeved on the outside of the inner nozzle module (10).

9. The multilayer microfluidic coaxial extrusion printing nozzle according to claim 1, characterized in that, The end of the side inlet (25) is provided with a standardized leak-free quick-connect connector.

10. A method for bioprinting using the multilayer microfluidic coaxial extrusion printing nozzle according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1: The outer layer printing material is injected into the annular pressure stabilizing cavity (22) from the side inlet (25), so that the outer layer printing material impacts the flow column (23) to obtain two streams of split material flowing symmetrically along both sides of the flow column (23); S2: The two split material streams flow circumferentially along the annular pressure stabilizing cavity (22) and merge. The wall surface of the annular pressure stabilizing cavity (22) is used to shear and dissipate the merged outer printing material to obtain an annular pressure stabilizing material stream with uniform circumferential velocity distribution. S3: Introduce the annular pressure-stabilizing material flow into the tapered channel (26), accelerate it along the tapered inner wall and transition it into axial flow, and obtain a tapered extruded material flow with uniform axial velocity distribution; S4: Inject the inner layer printing material from the inner layer feed port (11) of the inner layer nozzle module (10), so that the inner layer printing material flows through the inner layer tapered channel (13) and the inner layer cylindrical outlet section (14) in sequence to obtain the inner layer axial material flow; S5: The tapered extruded material flow and the inner axial material flow are merged at the end outlet (30) of the cylindrical outlet section (27), so that the tapered extruded material flow coaxially covers the outside of the inner axial material flow, and a coaxial core shell structure is obtained and extruded.

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