Multistage aerodynamic nozzle based on suppression of aerosol inkjet printing satellite droplets

Abstract

A multi-stage aerodynamic nozzle for suppressing aerosol inkjet printing of satellite droplets includes a pneumatic focusing module and a multi-stage structured nozzle connected thereto. The pneumatic focusing module has a mixing chamber, and a carrier gas inlet and a sheath gas inlet are located at the upper end of the module, both of which are connected to the mixing chamber. The multi-stage structured nozzle has, from top to bottom, a connected mixing inlet, a mixing chamber, a first-stage inverted cone focusing structure inlet, a second-stage inverted cone focusing structure inlet, a third-stage inverted cone focusing structure inlet, a three-stage focused mixing outlet, a buffer section, an inverted cone structure outlet channel, and an aerosol jet outlet. This invention employs a synergistic control mechanism of pneumatic pre-focusing and multi-stage structured field focusing to achieve step-by-step shaping, stabilization, and collimation of the aerosol beam, thereby improving printing accuracy, stability, and process robustness.

Description

Technical Field

[0001] This invention relates to the field of aerosol inkjet printing technology, specifically to a multi-stage aerodynamic nozzle based on suppressing aerosol inkjet printing of satellite droplets. Background Technology

[0002] Aerosol inkjet printing, as an important branch of additive manufacturing technology, has become one of the core manufacturing methods in fields such as printed electronics, flexible circuits, and conformal sensors due to its advantages such as non-contact deposition, high resolution, wide material compatibility, and 3D conformal printing. This technology forms micron-sized aerosol particles by atomizing functional inks, which are then transported by a carrier gas and confined by a sheath gas to form a fine jet that is ejected onto the substrate. The core of its printing quality lies in the stability of the aerosol flow field and the controllability of the jet morphology.

[0003] In practical applications, aerosol inkjet printing commonly faces technical bottlenecks such as satellite droplets and over-spraying when printing high-density, fine structures. These phenomena can lead to blurred line edges, uncontrolled linewidth, and even short circuits caused by bridging, and the problems become more pronounced as the printing distance increases. Existing technologies mainly rely on a single sheath gas flow to constrain the aerosol beam, but the mechanism's control capability is limited. Increasing the sheath gas flow rate to pursue a finer beam can easily create turbulence within the nozzle, disrupting the stability of aerosol particle motion and exacerbating the generation of satellite droplets. At the same time, the beam constrained by a single sheath gas diverges rapidly after leaving the nozzle, significantly limiting the effective printing distance.

[0004] Currently, most aerosol printing nozzles are modified from dispensing nozzles. Their internal flow channels are mostly integral cones or simple axisymmetric cavities, which cannot precisely control the flow rate and path of the carrier gas and sheath gas. When aerosols enter the nozzle, they are prone to sudden pressure changes and velocity decay, which can lead to particle backflow, stagnation, or agglomeration. This increases the risk of nozzle clogging and further damages beam stability, exacerbating satellite droplet and overspray problems (Aerosol focusing in micro-capillaries: Theory and experiment, Aerosol Sci., 2008, 39, 691–709; Study of aerodynamicfocusing lens stacks (ALS) for long focal length aerosol-assisted focused chemical vapor deposition (AAFCVD), RSC Adv., 2021, 11, 4425). In addition, they lack structured shaping designs for aerosol flow fields, resulting in poor adaptability of beam morphology to different printing requirements.

[0005] Because the processes of aerosol generation, transport, and focusing are highly aerodynamically coupled, existing technologies can only indirectly optimize printing results by repeatedly adjusting the flow rate and ratio of carrier gas and sheath gas (Precision Control of Aerosol Jet Printing for Conformal Electronics Fabrication with Ultra-Fine and Wide-Range Resolution, Adv. Mater. Technol., 2025, 10, 2402114). This results in a strong dependence on process parameters, a narrow stable process window, and difficulty in ensuring printing repeatability and consistency. This problem is particularly prominent in the manufacturing of complex three-dimensional conformal structures, which severely limits the application of aerosol inkjet printing in high-reliability precision manufacturing.

[0006] In summary, the shortcomings of existing technologies in terms of nozzle structure and flow field control make it impossible to effectively suppress satellite droplets and overspray while ensuring printing efficiency, and it is also difficult to meet the high precision requirements of long printing distances. Therefore, there is an urgent need for a nozzle solution that achieves step-by-step shaping, stabilization and collimation of aerosol beams through multi-stage structured flow channels to improve printing accuracy, stability and process robustness. Summary of the Invention

[0007] In order to overcome the shortcomings of the prior art, the present invention aims to provide a multi-stage aerodynamic nozzle based on suppressing aerosol inkjet printing satellite droplets, so as to achieve step-by-step shaping, stabilization and collimation of aerosol beam, thereby improving printing accuracy, stability and process robustness.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A multi-stage aerodynamic nozzle for suppressing aerosol inkjet printing of satellite droplets includes a pneumatic focusing module 3 and a multi-stage structured nozzle 6 connected thereto; the pneumatic focusing module 3 has a mixing chamber 4 inside, and a carrier gas inlet 1 and a sheath gas inlet 2 at the upper end of the pneumatic focusing module 3, both of which are connected to the mixing chamber 4.

[0009] The multi-stage structured nozzle 6 has, from top to bottom, a connected gas mixing inlet 5, a gas mixing chamber 10, a first-stage inverted cone focusing structure inlet 11, a second-stage inverted cone focusing structure inlet 12, a third-stage inverted cone focusing structure inlet 13, a three-stage focusing gas mixing outlet 14, a buffer section 15, an inverted cone-shaped outlet channel 16, and an aerosol spray outlet 8.

[0010] The pneumatic focusing module 3 has an internal thread at its lower end and an external mounting thread 9 at its upper outer end. The thread engagement enables a detachable and secure connection, which ensures the structural stability after assembly and facilitates the maintenance and replacement of the nozzle later.

[0011] The pneumatic focusing module 3 is provided with a positioning groove at its lower end, and the multi-stage structured nozzle 6 is provided with an external positioning protrusion 7 in the middle. The external positioning protrusion 7 cooperates with the positioning component 17 to ensure the coaxiality of the multi-stage structured nozzle 6 and the pneumatic focusing module 3.

[0012] The cone angles of the first-stage inverted cone focusing structure inlet 11, the second-stage inverted cone focusing structure inlet 12, and the third-stage inverted cone focusing structure inlet 13 gradually decrease to enhance the gathering effect of the structure field on the aerosol beam.

[0013] The cone angle of the inlet 11 of the first-stage inverted cone focusing structure is 12°~21°, the cone angle of the inlet 12 of the second-stage inverted cone focusing structure is 7°~18°, the cone angle of the inlet 13 of the third-stage inverted cone focusing structure is 3°~10°, and the aperture shrinkage ratio of each stage structure is 1:0.9~1:0.4.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: (A) The present invention adopts a coordinated control mechanism of pneumatic pre-focusing and multi-stage structural field focusing, which not only avoids the defects of increasing flow rate and aggravating satellite droplet formation in the existing single sheath gas focusing mode, but also makes aerosol particles highly concentrated in the main flow path through the step-by-step constraint of the three-stage inverted cone structure, effectively suppressing the generation of satellite droplets and transition spraying, and significantly improving the clarity of printed line edges and the controllability of line width.

[0015] (B) The present invention employs a three-stage inverted conical focusing structure with a cone angle and aperture that gradually narrows along the flow direction, which can continuously and stably constrict the aerosol beam, greatly enhance the beam collimation, and significantly improve the effective printing distance compared to the existing single pneumatic focusing scheme.

[0016] (C) The present invention adopts a combination design of multi-stage inverted conical flow channels and buffer sections, which can reduce the backflow, retention and agglomeration of aerosol particles and reduce the risk of nozzle clogging; at the same time, it reduces flow field disturbance, so that the aerosol beam remains uniform and stable during the spraying process, and improves the repeatability and consistency of the printing process.

[0017] (D) The present invention adopts a dual positioning structure with external assembly threads and positioning protrusions. It achieves a fastening connection through fine thread and ensures the coaxiality of the printhead and nozzle through the cooperation of positioning protrusions and positioning grooves, avoiding beam offset caused by assembly eccentricity, and further improving the edge consistency of printed lines and graphic accuracy.

[0018] (E) The present invention uses a multi-stage structured nozzle and a pneumatic focusing module with a threaded detachable connection, which facilitates the cleaning, replacement and maintenance of the nozzle, reduces equipment downtime, and lowers the cost of use and maintenance difficulty. Attached Figure Description

[0019] Figure 1 This is an external view of the assembly structure of the pneumatic focusing module and the printing nozzle in an embodiment of the present invention.

[0020] Figure 2 This is a cross-sectional view of the assembly structure of the pneumatic focusing module and the printing nozzle in an embodiment of the present invention.

[0021] Figure 3 This is an external view of the assembly structure of the printing nozzle according to an embodiment of the present invention.

[0022] Figure 4 This is a cross-sectional view of the assembly structure of the printing nozzle in an embodiment of the present invention.

[0023] Figure 5 This is a cross-sectional view of the assembly process of the printing nozzle in an embodiment of the present invention.

[0024] Figure 6 This is a silver ink deposition pattern printed using focused printing according to an embodiment of the present invention.

[0025] In the diagram: 1-Carrier gas inlet; 2-Sheath gas inlet; 3-Pneumatic focusing module; 4-Mixing chamber; 5-Mixing inlet of the nozzle; 6-Multi-stage structured nozzle; 7-External positioning protrusion of the nozzle; 8-Aerosol jet outlet; 9-External assembly thread; 10-Cavity where the mixed gas enters the nozzle; 11-First-stage inverted cone focusing structure inlet; 12-Second-stage inverted cone focusing structure inlet; 13-Third-stage inverted cone focusing structure inlet; 14-Mixing outlet after three-stage focusing; 15-Buffer section; 16-Inverted cone structure outlet channel; 17-Positioning component. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0027] Example 1, such as Figure 1 and Figure 2As shown, a multi-stage aerodynamic nozzle for suppressing aerosol inkjet printing of satellite droplets includes a pneumatic focusing module 3 and a multi-stage structured nozzle 6 connected thereto. The pneumatic focusing module 3 has a mixing chamber 4 inside, and a carrier gas inlet 1 and a sheath gas inlet 2 at its upper end, both of which are connected to the mixing chamber 4. The carrier gas inlet 1 is used to transport the atomized aerosol particles into the mixing chamber 4. The sheath gas inlet 2 is used to connect to a sheath gas source, and the sheath gas and carrier gas are mixed in the mixing chamber 4 at a preset flow ratio to achieve aerodynamic pre-focusing of the aerosol beam. The lower end of the pneumatic focusing module 3 has an internal thread and a positioning groove, which are respectively connected to the multi-stage structured nozzle 6.

[0028] Reference Figure 2 , Figure 3 , Figure 4 and Figure 5 The multi-stage structured nozzle 6 has an external mounting thread 9 at its upper outer end and an external positioning protrusion 7 in its middle. The external mounting thread 9 and the internal thread at the lower end of the pneumatic focusing module 3 are matched to achieve a detachable and secure connection. Simultaneously, the external positioning protrusion 7 of the multi-stage structured nozzle 6 is embedded in the positioning component 17 to ensure coaxiality after assembly, preventing eccentricity of the aerosol stream during transmission. The multi-stage structured nozzle 6 has, from top to bottom, a connected gas mixing inlet 5, a gas mixing chamber 10, a first-stage inverted cone focusing structure inlet 11, a second-stage inverted cone focusing structure inlet 12, a third-stage inverted cone focusing structure inlet 13, a three-stage focused gas mixing outlet 14, a buffer section 15, an inverted cone-shaped outlet channel 16, and an aerosol spray outlet 8. The gas mixing inlet 5 is connected to the gas mixing chamber 4, and the aerosol mixture after pneumatic pre-focusing enters the nozzle's gas mixing chamber 10 from the gas mixing inlet 5. Downstream of the gas mixing chamber 10… The inlet 11 of the first-stage inverted cone focusing structure, the inlet 12 of the second-stage inverted cone focusing structure, and the inlet 13 of the third-stage inverted cone focusing structure are connected sequentially. Along the aerosol flow direction, the cone angle of the three-stage inverted cone focusing structures decreases step by step, and the aperture gradually narrows synchronously, so as to realize the gradual convergence of the structural field of the aerosol beam. The downstream of the third-stage inverted cone focusing structure is connected to the buffer section 15 through the mixed gas outlet 14 after the three-stage focusing. The buffer section 15 is a cylindrical cavity used to weaken the residual disturbance of the flow field after multi-stage focusing, so that the state of the aerosol beam tends to be uniform and stable. The downstream of the buffer section 15 is connected to the outlet channel 16 of the inverted cone structure. The taper of the outlet channel 16 of the inverted cone structure matches the end taper of the third-stage inverted cone focusing structure, so as to realize the smooth transition and final collimation of the beam from the buffer section 15 to the injection end. The end of the outlet channel 16 of the inverted cone structure is connected to the aerosol injection outlet 8. The aerosol beam after focusing and stabilization is ejected from the outlet and deposited on the substrate surface.

[0029] In use, the atomized functional ink aerosol enters the mixing chamber 4 from the carrier gas inlet 1 via the carrier gas. Simultaneously, sheath gas enters the mixing chamber 4 from the sheath gas inlet 2. The sheath gas and carrier gas are mixed in a preset ratio to pneumatically pre-focus the aerosol beam. The pre-focused mixed gas flows from the mixing inlet 5 into the mixing chamber 10 of the multi-stage structured nozzle 6, and then sequentially passes through the first, second, and third stage inverted conical focusing structures: the first stage inverted conical focusing structure provides initial structural constraint on the pre-focused beam, gently guiding the particles to converge towards the center; the second stage inverted conical focusing structure further compresses the radial range of the beam, enhancing the main path following ability of the particles; the third stage inverted conical focusing structure deeply converges the beam, making the particles highly concentrated on the main flow path; the beam focused by the three-stage structured field enters the buffer section 15 for stabilization after passing through the mixing outlet 14, and finally, after being collimated by the inverted conical structure outlet channel 16, it is ejected from the aerosol jet outlet 8, completing the high-precision printing deposition.

[0030] To further enhance the focusing effect, in Example 1, along the aerosol flow direction, the cone angle of the inlet 11 of the first-stage inverted cone focusing structure is 10°~15°, the cone angle of the inlet 12 of the second-stage inverted cone focusing structure is 10°~15°, and the cone angle of the inlet 13 of the third-stage inverted cone focusing structure is 3°~8°. The aperture shrinkage ratio of each structure is 1:0.8~1:0.5. The continuous and stable beam convergence is achieved through the gradual structural constraint.

[0031] To ensure ease of assembly and maintenance, the external assembly thread 9 in this embodiment adopts a fine thread design with a thread accuracy of 6H / 6g, which not only ensures the sealing performance of the connection but also facilitates manual screwing operation; the height of the external positioning protrusion 7 and the depth clearance of the positioning groove of the pneumatic focusing module 3 are matched (clearance ≤ 0.01mm), which further improves the coaxiality accuracy of the nozzle and the spray head.

[0032] The aerosol inkjet printing effect in this embodiment is as follows: Figure 6 As shown, the trajectory of the silver ink deposition shows no obvious satellite droplets or overspray, proving that the inverted cone-shaped structured nozzle has excellent focusing effect.

[0033] Example 2: To further enhance the focusing effect, in Example 2, along the aerosol flow direction, the cone angle of the inlet 11 of the first-stage inverted cone focusing structure is 15°~20°, the cone angle of the inlet 12 of the second-stage inverted cone focusing structure is 8°~18°, and the cone angle of the inlet 13 of the third-stage inverted cone focusing structure is 5°~10°. The aperture shrinkage ratio of each stage structure is 1:0.7~1:0.4. Continuous and stable beam convergence is achieved through gradual structural constraints. To ensure ease of assembly and maintenance, in this example, the height of the external positioning protrusion 7 of the external mounting thread 9 is matched with the depth of the positioning groove of the pneumatic focusing module 3 (gap ≤ 0.02mm), further improving the coaxiality accuracy of the nozzle and the spray head.

[0034] The aerosol inkjet printing effect in this embodiment is similar to that in Embodiment 1.

[0035] Example 3: To further enhance the focusing effect, in Example 3, along the aerosol flow direction, the cone angle of the inlet 11 of the first-stage inverted cone focusing structure is 12°~21°, the cone angle of the inlet 12 of the second-stage inverted cone focusing structure is 7°~17°, and the cone angle of the inlet 13 of the third-stage inverted cone focusing structure is 4°~9°. The aperture shrinkage ratio of each stage structure is 1:0.9~1:0.6. Continuous and stable beam convergence is achieved through gradual structural constraints. To ensure ease of assembly and maintenance, in this example, the height of the external positioning protrusion 7 of the external mounting thread 9 is fitted with the depth of the positioning groove of the pneumatic focusing module 3 (gap ≤ 0.03mm), further improving the coaxiality accuracy of the nozzle and the spray head.

[0036] The aerosol inkjet printing effect in this embodiment is similar to that in Embodiment 1.

Claims

1. A multi-stage aerodynamic nozzle for suppressing aerosol inkjet printing of satellite droplets, characterized in that: It includes a pneumatic focusing module (3) and a multi-stage structured nozzle (6) connected thereto; the pneumatic focusing module (3) is provided with a mixing chamber (4) inside, and the upper end of the pneumatic focusing module (3) is provided with a carrier gas inlet (1) and a sheath gas inlet (2), and the carrier gas inlet (1) and the sheath gas inlet (2) are both connected to the mixing chamber (4).

2. The multi-stage aerodynamic nozzle for suppressing aerosol inkjet printing of satellite droplets according to claim 1, characterized in that: The multi-stage structured nozzle (6) is provided with the following components in sequence from top to bottom: a gas mixing inlet (5), a gas mixing chamber (10), a first-stage inverted cone focusing structure inlet (11), a second-stage inverted cone focusing structure inlet (12), a third-stage inverted cone focusing structure inlet (13), a gas mixing outlet after three-stage focusing (14), a buffer section (15), an inverted cone-shaped outlet channel (16), and an aerosol spray outlet (8).

3. The multi-stage aerodynamic nozzle for suppressing aerosol inkjet printing of satellite droplets according to claim 2, characterized in that: The pneumatic focusing module (3) has an internal thread at its lower end and an external assembly thread (9) at the upper end of the multi-stage structured nozzle (6), which can be detached and fastened by thread engagement.

4. A multi-stage aerodynamic nozzle for suppressing aerosol inkjet printing of satellite droplets according to claim 3, characterized in that: The pneumatic focusing module (3) is provided with a positioning groove at its lower end, and the multi-stage structured nozzle (6) is provided with an external positioning protrusion (7) in the middle. The external positioning protrusion (7) cooperates with the positioning component (17) to ensure the coaxiality of the multi-stage structured nozzle (6) and the pneumatic focusing module (3).

5. A multi-stage aerodynamic nozzle for suppressing aerosol inkjet printing of satellite droplets according to claim 2, characterized in that: The cone angles of the first-stage inverted cone focusing structure inlet (11), the second-stage inverted cone focusing structure inlet (12), and the third-stage inverted cone focusing structure inlet (13) gradually decrease to enhance the gathering effect of the structure field on the aerosol beam.

6. A multi-stage aerodynamic nozzle for suppressing aerosol inkjet printing of satellite droplets according to claim 5, characterized in that: The cone angle of the first-stage inverted cone focusing structure inlet (11) is 12°~21°, the cone angle of the second-stage inverted cone focusing structure inlet (12) is 7°~18°, the cone angle of the third-stage inverted cone focusing structure inlet (13) is 3°~10°, and the aperture shrinkage ratio of each stage structure is 1:0.9~1:0.4.

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