An acoustic-flow field coupled aerosol inkjet printing system and method

Abstract

This invention discloses an acoustic-flow field coupled aerosol inkjet printing system and method, relating to the fields of micro-nano manufacturing and advanced 3D electronic printing technology. It includes a pneumatic control module, an ultrasonic atomization module, an acoustic-flow field coupled focusing module, and a printing and deposition module connected in sequence. The acoustic-flow field coupled focusing module includes a nozzle with a multi-stage aerodynamic focusing lens structure inside, and a piezoelectric tube on the outer wall of the nozzle, connected via a power amplifier and a signal amplifier. The multi-stage lens structure flow field reconstructs the streamlines of the coaxial jet, significantly increasing the local particle transport flux of the substrate, forcing the deposited material to accumulate normally to achieve vertical lift. Simultaneously, the piezoelectric tube constructs a confined ultrasonic standing wave field inside the nozzle, performing non-contact secondary extreme convergence of aerosol particles. This invention fundamentally solves the problem of "aerodynamic collapse," achieving high-precision and stable manufacturing of high-steepness, high aspect ratio 3D micro-nano structures.

Description

Technical Field

[0001] This invention relates to the fields of micro-nano manufacturing and advanced 3D electronic printing technology, specifically to an acoustic-flow field coupled aerosol inkjet printing system and method. Background Technology

[0002] With the rapid development of microelectromechanical systems (MEMS), 3D stacked packaging, and cross-scale interconnect technologies, the demand for micro / nano manufacturing is shifting from simple "two-dimensional planar patterning" to "high aspect ratio three-dimensional solidification." Aerosol inkjet printing, as a non-contact direct-writing technology with broad material adaptability, has become a key technological path for manufacturing three-dimensional microelectrodes, microfluidic vertical interconnect structures, and complex biological scaffolds due to its potential to overcome uneven surfaces and perform microscale three-dimensional stacking. The core of this technology lies in using sheath gas to focus atomized functional materials into microjets and achieving the "growth" of three-dimensional structures through multi-layer continuous deposition. The forming quality depends on the collimation of the aerosol jet during the flight phase and its morphology retention capability during the deposition phase.

[0003] When constructing high aspect ratio fine structures such as micropillar arrays and suspended beams, existing aerosol inkjet printing ([1] Seiti M, Degryse O, Monica Ferraro R, et al. 3D aerosol jet® printing for microstructuring: advantages and limitations [J]. International Journal of Bioprinting, 2023, 9(6): 57–74;[2] Sharma M, Seiti M. Machine learning-based printability assessment and process control of aerosol jet 2D and 3D printed PEDOT:PSS-based microstructures [J]. Virtual and Physical Prototyping, 2025,20(1): 2575397;[3] Ceretti E, Sharma M, Ferraris E, et al. Printability assessment and modelling for process optimization of 3D aerosol jet® printed high aspect ratio microstructures [J]. CIRP Annals, 2025, 74(1): 287–291; [4] Smith BN, Ballentine P, Doherty JL, et al. Aerosol jet printing conductive3D microstructures from graphene without post-processing [J]. Small, 2024, 20(12): 2305170; [5] Vlnieska V, Gilshtein E, Kunka D, et al. Aerosol jet printing of 3D pillar arrays from photopolymer ink[J].Polymers, 2022, 14(16): 3411) generally faces the technical bottleneck of "aerodynamic collapse" and morphological loss of control: During the vertical growth of such structures, as the height increases, the continuous high-speed sheath airflow field will directly impact the incompletely solidified flexible deposit, which can easily cause the microstructure to sway, tilt, or even collapse; and the Karman vortex street or local turbulence generated when the airflow passes through the micro-columns will blow away the deposited material, resulting in rough sidewalls and uneven diameters, making it difficult to obtain an ideal three-dimensional morphology with high steepness and surface smoothness.

[0004] Existing technologies mainly rely on adjusting the sheath flow rate or optimizing the nozzle geometry to try to balance the contradiction between focusing and impact ([6] Sharma M, Seiti M. Machine learning-based printability assessment and process control of aerosol jet 2D and 3D printed PEDOT: PSS-based microstructures[J]. Virtual and Physical Prototyping, 2025, 20(1): 2575397; [7] Gamba L, Diaz-Arauzo S, Hersam MC, et al. Aerosol jet printing of phase-inversion graphene inks for high-aspect-ratio printed electronics and sensors[J]. ACS Applied Nano Materials, 2023, 6(22): 21133-21140; [8] Shakur MS, Sakib MN, Inman E, et al. Design and fabrication of a micro-nozzle for aerosol jet printing[J]. 2024.), but this mechanism has natural physical limitations: if the sheath flow rate is reduced to reduce the impact on the microstructure, the aerosol jet will diverge rapidly due to the loss of constraint, resulting in a larger deposition spot and forming a wide top structure in the shape of a "mushroom head", thus losing printing resolution; if a high flow rate is maintained to ensure focusing accuracy, the aerodynamic impact force is significantly enhanced, and the weak liquid surface tension cannot resist the airflow shear, resulting in the root of the structure breaking or severe deformation. In addition, existing acoustic field-assisted printing technology ([9] Ma T, Li Y, Cheng H, et al. Enhanced aerosol-jetprinting using annular acoustic field for high resolution and minimaloverspray[J]. Nature Communications, 2024, 15(1): 6317.) is mostly limited to acoustic focusing inside the nozzle, which only solves the problem of refining the jet "before it flies out", and lacks active intervention means for the fluid dynamic behavior of the jet on the substrate "after it touches".

[0005] Because the three-dimensional deposition process involves complex gas-liquid-solid multiphase interface dynamics, existing technologies (

[10] Hu C, Jahan S, Yuan B, et al. 3D‐AJP: fabrication of advanced microarchitected multimaterial ceramic structures via binder‐free and auxiliary‐free aerosoljet 3D nanoprinting[J]. Advanced Science, 2025, 12(15): 2405334;

[11] Mosa MA, Jo JY, Park SH, et al. Aerosol printing of 3D conductive microstructures via precision dot modulation [J]. Small, 2025, 21(31): 2504037;

[12] Ali MA, Hu C, Yuan B, et al. Breaking the barrier to biomolecule limit-of-detection via 3D printed multi-length-scale graphene-coated electrodes [J]. Nature Communications, 2021, 12(1): 7077;

[13] Ali MA, Hu C, Jahan S, et al. Sensing of COVID-19 antibodies in seconds via aerosol jet nanoprinted reduced-graphene-oxide-coated 3D electrodes [J]. Advanced Materials, 2021, 33(7):2006647.) In the absence of external field assistance, passive molding relies solely on the material's natural drying and viscosity characteristics, resulting in extreme sensitivity to ink rheology and a very narrow stable process window. During long-term printing, minute airflow fluctuations or focal length changes are amplified layer by layer, leading to the accumulation of growth defects. This makes it impossible for existing technologies to continuously and stably manufacture highly consistent, high aspect ratio three-dimensional array structures while ensuring fine feature dimensions.

[0006] In summary, the shortcomings of existing technologies in three-dimensional deposition dynamics control and airflow interference resistance prevent them from effectively resolving the contradiction between high-speed airflow impact and flexible structure growth, and also make it difficult to achieve in-situ active shaping of the deposit morphology. Therefore, there is an urgent need for a new printing device and method to control aerosol jet focusing and deposition in order to overcome the application limitations of aerosol inkjet printing in the field of complex three-dimensional micro-nano manufacturing. Summary of the Invention

[0007] In order to overcome the shortcomings of the prior art, the present invention aims to provide an acoustic-flow field coupled aerosol inkjet printing system and method. By introducing the coupling effect of acoustic field and structural flow field, the secondary fine focusing of the jet is achieved, and the morphology of the deposit is actively shaped, thereby realizing the stable manufacturing of large aspect ratio three-dimensional microstructures with high steepness and high surface smoothness.

[0008] To achieve the above objectives, the present invention provides the following solution: An acoustic-flow field coupled aerosol inkjet printing system includes a pneumatic control module, an ultrasonic atomization module, an acoustic-flow field coupled focusing module, and a printing and deposition module connected in sequence.

[0009] The pneumatic control module includes a flow and voltage integrated controller. The air inlet of the flow and voltage integrated controller is connected to a gas storage cylinder through an air inlet pipe. The gas storage cylinder contains inert gas. The first gas output end and the second gas output end of the flow and voltage integrated controller are respectively connected to the carrier gas transmission pipe and the sheath gas transmission pipe, thereby dividing the input gas into two paths: carrier gas and sheath gas.

[0010] The ultrasonic atomization module includes an atomization chamber, an atomization medium at the bottom of the chamber, an ink tank containing ink to be printed, a carrier gas transmission pipeline at the top of the ink tank, and an aerosol transmission pipeline at the top of the ink tank. An ultrasonic atomizer is installed at the bottom of the atomization chamber, and the electrical control terminal of the ultrasonic atomizer is connected to an integrated flow and voltage controller. When the ultrasonic atomizer is working, it atomizes the ink into aerosol particles. The carrier gas enters the ink tank through the carrier gas transmission pipeline, mixes with the suspended aerosol particles to form an aerosol bundle, and then enters the aerosol transmission pipeline.

[0011] The acoustic-flow field coupling focusing module includes a pneumatic focusing head, the upper end of which is connected to an aerosol transmission pipeline and a sheath gas transmission pipeline. Inside the pneumatic focusing head, sheath gas surrounds the aerosol bundle on the periphery, forming a coaxial "gas-solid-liquid" multiphase flow, and the initial pneumatic focusing is completed by relying on fluid dynamics constraints. The lower end of the pneumatic focusing head is tightly connected to the nozzle through an adapter.

[0012] The nozzle employs a multi-stage aerodynamic focusing lens structure with a gradually narrowing internal flow channel. When the coaxial jet after initial focusing is introduced into this channel, the outer sheath gas forms a constrained flow field with a significant radial pressure gradient. The trajectory of the outermost aerosol particles is forced to deviate sharply from and converge toward the central axis. During the multi-stage contraction process, the actual flight path of the particles becomes significantly longer and exhibits a highly convergent state, resulting in a substantial increase in the particle transport flux reaching the same microscopic cross-section of the substrate. This drives the particles to achieve vertical accumulation layer by layer in an extremely small area, enabling the upward lifting of the micropillars and suppressing the lateral spreading of the material.

[0013] The outer wall of the nozzle is connected to a piezoelectric tube, which is connected to a power amplifier and a signal amplifier. The high-frequency alternating electrical signal generated by the signal generator is amplified by the power amplifier and drives the piezoelectric tube to generate ultrasonic vibration. The high-frequency vibration passes through the outer wall of the nozzle and is directly coupled to the multi-level aerodynamic lens structure area inside the nozzle, constructing an ultrasonic standing wave field in the internal fluid medium. Aerosol particles flowing through this internal structure area are driven by the acoustic radiation force to gather towards the central axis of the flow channel, achieving extremely fine secondary focusing.

[0014] The printing and deposition module includes a multi-degree-of-freedom motion platform with a substrate fixed on it. The substrate is continuously sprayed by the nozzle, and the ink is stacked and cured layer by layer on the substrate, eventually growing into a three-dimensional micro-pillar with a large aspect ratio.

[0015] An acoustic-flow field coupled aerosol inkjet printing method includes the following steps: Step 1: Inject ink, place the substrate, and calibrate the printing distance; set the carrier gas and sheath gas flow parameters and atomization voltage, and configure the piezoelectric tube drive frequency and power; Step 2: Start the ultrasonic atomizer to atomize the ink into aerosol particles, mix them with the carrier gas to form aerosol bundles, and deliver them to the pneumatic focusing head through the aerosol delivery pipeline; Step 3: Inside the pneumatic focusing head, the sheath gas surrounds the aerosol bundle in the form of a ring flow field, performing preliminary coaxial physical compression on the aerosol particles, completing the initial pneumatic focusing, and forming a stable coaxial jet. Step 4: The jet enters the nozzle of the multi-stage lens, and the streamline is reconstructed by the structured flow field to improve the local flux, and the internal ultrasonic standing wave is superimposed to achieve non-contact ultimate convergence. Step 5: Under the protection of a steady fluid, and in conjunction with the movement of the motion platform, the particles are vertically stacked with a high degree of steepness.

[0016] Compared with the prior art, the present invention has the following significant advantages: 1. Enhancing Structural Flow Field Stability and Overcoming Aerodynamic Collapse Bottlenecks: Unlike traditional technologies that rely solely on airflow propulsion, this invention utilizes a specific structural flow field formed by multi-stage aerodynamic lenses to optimize the flow field dynamics of sheath gas at the deposition end. This structural flow field effectively mitigates the direct shear force of high-speed airflow on incompletely solidified microstructures, providing a stable fluid network for the vertical growth of three-dimensional micropillars. It fundamentally solves the problems of swaying, tilting, or collapse of high aspect ratio structures during growth, and is key to achieving large aspect ratio three-dimensional manufacturing.

[0017] 2. Ultimate Acoustic Field Focusing for Significantly Improved Printing Resolution: Based on stable transport within the structural flow field, this system introduces a secondary acoustic field intervention mechanism. Utilizing acoustic radiation force, it applies extreme radial constraint to aerosol particles, resulting in secondary refinement of the jet before ejection. This acoustic-aerodynamic coupling mode achieves a finer deposition spot than traditional aerodynamic focusing without interfering with the stability of the structural flow field, effectively avoiding growth defects such as mushroom-shaped nozzles and achieving extremely high collimation and minimal linewidth.

[0018] 3. Synergistic interaction of field forces enhances the consistency of 3D morphology: The structural flow field ensures the collimation of 3D structure growth, while the acoustic field ensures the refinement of the jet stream. The synergistic effect of these two factors enables in-situ active control of the deposition process. The printed micropillar arrays and other structures exhibit excellent sidewall steepness and surface smoothness, significantly reducing the error accumulation during long-term printing of 3D micro / nano structures.

[0019] 4. Expanding the process window and reducing dependence on ink rheological properties: Since the structural flow field provides the main morphological support and the acoustic field provides the core focusing and convergence function, this method greatly reduces the dependence on the viscosity and surface tension of the functional ink itself. Even low-viscosity inks can achieve highly consistent three-dimensional stacking under the dual protection of the structural flow field and the acoustic field, greatly expanding their application scope in fields such as flexible electronics and biochips. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the acoustic-flow field coupled aerosol inkjet printing system according to an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the acoustic-flow field coupling focusing principle in an embodiment of the present invention.

[0022] Figure 3 This is a schematic diagram of the jet deposition effect under the acoustic-flow field coupling focusing effect in an embodiment of the present invention.

[0023] Figure 4 This is a schematic diagram of the particle motion trajectory in the structural flow field in an embodiment of the present invention.

[0024] Figure 5This is a flowchart of an acoustic-flow field coupled aerosol inkjet printing method according to an embodiment of the present invention.

[0025] Figure 6 This is a schematic diagram of the morphology of aerosol inkjet-printed micropillars under the influence of only the structural flow field.

[0026] Figure 7 This is a schematic diagram of the morphology of aerosol inkjet-printed micropillars under the action of an acoustic-fluid coupling field.

[0027] Figure 8 This is a schematic diagram illustrating the morphological evolution of aerosol inkjet-printed micropillar structures when acoustic field assistance is activated mid-printing.

[0028] Among them: 1-Gas storage cylinder, 2-Inlet pipeline, 3-Flow and voltage integrated controller, 4-Carrier gas transmission pipeline, 5-Sheath gas transmission pipeline, 6-Ultrasonic atomizer, 7-Atomizing medium, 8-Atomizing chamber, 9-Ink tank, 10-Ink, 11-Carrier gas, 12-Sheath gas, 13-Aerosol transmission pipeline, 14-Aerosol bundle, 15-Pneumatic focusing head, 16-Adapter, 17-Nozzle, 18-Piezoelectric tube, 19-Substrate, 20-Motion platform, 21-Power amplifier, 22-Signal amplifier, 23-Aerosol particles, 24-Micro column. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] like Figure 1 As shown, an acoustic-flow field coupled aerosol inkjet printing system includes a pneumatic control module, an ultrasonic atomization module, an acoustic-flow field coupled focusing module, and a printing and deposition module connected in sequence.

[0031] The pneumatic control module includes a flow-voltage integrated controller 3. The air inlet of the flow-voltage integrated controller 3 is connected to the gas storage cylinder 1 through the air inlet pipe 2. The gas storage cylinder 1 stores inert gas. The flow-voltage integrated controller 3 plays a central regulating role in this system. Its first gas output end and second gas output end are connected to the carrier gas transmission pipe 4 and the sheath gas transmission pipe 5, respectively, thereby dividing the input gas into two paths: carrier gas 11 and sheath gas 12.

[0032] The ultrasonic atomization module includes an atomization chamber 8, with an atomization medium 7 (usually water) at the bottom of the inner side of the atomization chamber 8. An ink tank 9 is placed in the atomization medium 7, containing ink 10 to be printed. The upper side of the ink tank 9 is connected to a carrier gas transmission pipeline 4, and the top of the ink tank 9 is connected to an aerosol transmission pipeline 13. An ultrasonic atomizer 6 is installed at the bottom of the atomization chamber 8, and the electrical control terminal of the ultrasonic atomizer 6 is connected to a flow and voltage integrated controller 3. Under the voltage regulation of the controller, the high-frequency oscillation generated by the ultrasonic atomizer 6 during operation is transmitted to the ink tank 9 through the atomization medium 7, atomizing the ink 10 into aerosol particles 23. At this time, the carrier gas 11 enters the ink tank 9 through the carrier gas transmission pipeline 4, and mixes thoroughly with the suspended aerosol particles 23 to form a high-concentration aerosol bundle 14, which then enters the aerosol transmission pipeline 13.

[0033] The aforementioned acoustic-flow field coupling focusing module is the core component for achieving high-resolution and high aspect ratio printing, such as... Figure 2 and Figure 3 As shown, it includes a pneumatic focusing head 15, the upper end of which is connected to an aerosol delivery pipeline 13 and a sheath gas delivery pipeline 5. Inside the pneumatic focusing head 15, sheath gas 12 surrounds the aerosol bundle 14 on the periphery, forming a coaxial "gas-solid-liquid" multiphase flow, and the initial pneumatic focusing is completed here by means of fluid dynamic constraints. The lower end of the pneumatic focusing head 15 is tightly connected to the nozzle 17 through an adapter 16.

[0034] The nozzle 17 employs a multi-stage aerodynamic focusing lens structure, with a gradually narrowing internal flow channel. When the coaxial jet after initial focusing is introduced into this channel, guided by the inner wall geometry, the outer sheath gas 12 forms a constrained flow field with a significant radial pressure gradient. Figure 4 As shown, the trajectory of the outermost aerosol particles is forced to deviate sharply from and converge toward the central axis. During the multi-stage contraction process, the actual flight path of the particles becomes significantly longer and exhibits a highly convergent state, resulting in a substantial increase in the particle transport flux reaching the same microscopic section of the substrate 19. This drives the particles to achieve vertical accumulation layer by layer in an extremely small area, successfully achieving the upward lifting of the column and suppressing the lateral spread of the material. In addition, this design maintains a jet shape with extremely high collimation and effectively suppresses local turbulence at the nozzle, fundamentally offsetting the lateral shearing and scouring damage of the high-speed airflow to the incompletely solidified micro-pillars 24.

[0035] The outer wall of the nozzle 17 is connected to a piezoelectric tube 18, which is connected to a power amplifier 21 and a signal amplifier 22. The signal generator 22 generates a high-frequency alternating electrical signal of a specific frequency, which is amplified by the power amplifier 21 and drives the piezoelectric tube 18 to generate ultrasonic vibration. This high-frequency vibration passes through the outer wall of the nozzle 17 and is directly coupled to the multi-level aerodynamic lens structure area inside the nozzle 17, constructing a stable ultrasonic standing wave field in the internal fluid medium. The area of ​​action of this ultrasonic field is strictly limited to the internal structural area of ​​the nozzle 17 to assist jet focusing, and will not overflow downwards to directly act on the deposition area below, thereby avoiding the impact and damage of the flexible microstructure deposited on the substrate 19 by the sound pressure. The aerosol particles 23 flowing through this internal structural area are driven by the sound radiation force to gather towards the central axis of the flow channel, achieving extremely fine secondary focusing.

[0036] Reference Figure 1 , Figure 3 The printing and deposition module includes a multi-degree-of-freedom motion platform 20, on which a substrate 19 is fixed. The substrate 19 cooperates with the continuous spraying of the nozzle 17, and the ink is stacked and solidified layer by layer on the substrate, eventually growing into a three-dimensional micro-pillar 24 with a large aspect ratio. The aerosol jet, which is deeply converging inside the acoustic-flow field, is ejected from the tiny aperture at the bottom of the nozzle 17. Because the structural flow field effectively regulates the flow field dynamics in the flow channel, it reduces the radial divergence and impact of the high-speed airflow after leaving the nozzle, so that the jet reaches the substrate 19 with extremely high collimation.

[0037] Reference Figure 5 A method for acoustic-fluid field coupled aerosol inkjet printing includes the following steps: Step 1: System Initialization and Parameter Setting. Inject ink, place substrate 19, and calibrate the printing distance; set the carrier gas and sheath gas flow parameters and atomization voltage, and configure the piezoelectric tube drive frequency and power; Step 2: Aerosol generation and transport. The ultrasonic atomizer 6 is activated to atomize the ink 10 into aerosol particles, which are then mixed with the carrier gas 11 to form an aerosol bundle 14, which is then transported to the pneumatic focusing head 15 through the aerosol transport pipeline 13. Step 3: Initial pneumatic focusing. Inside the pneumatic focusing head 15, the sheath gas 12 surrounds the aerosol bundle 14 in the form of a ring-shaped flow field, performing initial coaxial physical compression on the aerosol particles 23, completing the initial pneumatic focusing, and forming a stable coaxial jet; Step 4: Acoustic-flow field coupling secondary focusing and active deformation. The jet enters the multi-stage lens nozzle 17, where the streamlines are reconstructed using the structural flow field to improve local flux, and internal ultrasonic standing waves are superimposed to achieve non-contact ultimate focusing; Step 5: Co-growth of three-dimensional microstructures. Under the protection of a steady fluid, and in conjunction with the movement of the motion platform 20, the highly steep vertical stacking of microparticles is completed; Step Six: Post-curing and apparatus cleaning. The three-dimensional microstructure is post-cured according to the characteristics of ink 10 and substrate 19; subsequently, the apparatus is cleaned.

[0038] To further verify the beneficial effects of this system and method, this embodiment provides three sets of experimental morphology comparisons: like Figure 6 As shown, without the acoustic field activated, the structural flow field effectively overcomes the tilting and "aerodynamic collapse" phenomena caused by high-speed airflow, achieving stable vertical growth of the micro-column 24. Figure 7 As shown, under the influence of the acoustic-fluid coupling field throughout the process, the jet underwent secondary extreme focusing by acoustic radiation force while maintaining its original excellent vertical growth stability. The resulting micropillar 24 not only has steep and smooth sidewalls but also a significantly reduced diameter, successfully achieving an ultra-high resolution upright three-dimensional structure with a large aspect ratio. Figure 8 As shown, when the sound field is dynamically turned on during printing, it can be clearly observed that the micro-pillar 24 changes from a relatively thick, upright shape at the bottom to an extremely thin, upright micro-pillar at the top in an instant. This process directly confirms the role of the structural flow field as a stable growth foundation, as well as the decisive advantage of superimposed sound field in breaking through physical limits and achieving extremely fine jets.

Claims

1. A sound-flow field coupled aerosol inkjet printing system, characterized in that: It includes a pneumatic control module, an ultrasonic atomization module, an acoustic-flow field coupling focusing module, and a printing and deposition module connected in sequence; The acoustic-flow field coupling focusing module includes a pneumatic focusing head, with the upper end of the pneumatic focusing head connected to an aerosol transmission pipeline and a sheath gas transmission pipeline. Inside the pneumatic focusing head, sheath gas surrounds the aerosol bundle on the periphery, forming a coaxial "gas-solid-liquid" multiphase flow, and the initial pneumatic focusing is completed by relying on fluid dynamic constraints. The lower end of the pneumatic focusing head is connected to the nozzle through an adapter.

2. The acoustic-flow field coupled aerosol inkjet printing system according to claim 1, characterized in that: The outer wall of the nozzle is connected to a piezoelectric tube, which is connected to a power amplifier and a signal amplifier. The high-frequency alternating electrical signal generated by the signal generator is amplified by the power amplifier and drives the piezoelectric tube to generate ultrasonic vibration. The high-frequency vibration passes through the outer wall of the nozzle and is directly coupled to the multi-level aerodynamic lens structure area inside the nozzle, constructing an ultrasonic standing wave field in the internal fluid medium. Aerosol particles flowing through this internal structure area are driven by the acoustic radiation force to gather towards the central axis of the flow channel, achieving extremely fine secondary focusing.

3. The acoustic-flow field coupled aerosol inkjet printing system according to claim 1, characterized in that: The nozzle employs a multi-stage aerodynamic focusing lens structure with a gradually narrowing internal flow channel. When the coaxial jet after initial focusing is introduced into this channel, the outer sheath gas forms a constrained flow field with a significant radial pressure gradient. The trajectory of the outermost aerosol particles is forced to deviate sharply from and converge toward the central axis. During the multi-stage contraction process, the actual flight path of the particles becomes significantly longer and exhibits a highly convergent state, resulting in a substantial increase in the particle transport flux reaching the same microscopic cross-section of the substrate. This drives the particles to achieve vertical accumulation layer by layer in an extremely small area, enabling the upward lifting of the micropillars and suppressing the lateral spreading of the material.

4. The acoustic-flow field coupled aerosol inkjet printing system according to claim 1, characterized in that: The ultrasonic atomization module includes an atomization chamber, an atomization medium at the bottom of the chamber, an ink tank containing ink to be printed, a carrier gas transmission pipeline at the top of the ink tank, and an aerosol transmission pipeline at the top of the ink tank. An ultrasonic atomizer is installed at the bottom of the atomization chamber, and the electrical control terminal of the ultrasonic atomizer is connected to an integrated flow and voltage controller. When the ultrasonic atomizer is working, it atomizes the ink into aerosol particles. The carrier gas enters the ink tank through the carrier gas transmission pipeline, mixes with the suspended aerosol particles to form an aerosol bundle, and then enters the aerosol transmission pipeline.

5. The acoustic-flow field coupled aerosol inkjet printing system according to claim 1, characterized in that: The pneumatic control module includes a flow and voltage integrated controller. The air inlet of the flow and voltage integrated controller is connected to a gas storage cylinder through an air inlet pipe. The gas storage cylinder contains inert gas. The first gas output end and the second gas output end of the flow and voltage integrated controller are respectively connected to the carrier gas transmission pipe and the sheath gas transmission pipe, thereby dividing the input gas into two paths: carrier gas and sheath gas.

6. The acoustic-flow field coupled aerosol inkjet printing system according to claim 1, characterized in that: The printing and deposition module includes a multi-degree-of-freedom motion platform with a substrate fixed on it. The substrate is continuously sprayed by the nozzle, and the ink is stacked and cured layer by layer on the substrate, eventually growing into a three-dimensional micro-pillar with a large aspect ratio.

7. A sound-flow field coupled aerosol inkjet printing method, employing the sound-flow field coupled aerosol inkjet printing system according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Inject ink, place the substrate, and calibrate the printing distance; set the carrier gas and sheath gas flow parameters and atomization voltage, and configure the piezoelectric tube drive frequency and power; Step 2: Start the ultrasonic atomizer to atomize the ink into aerosol particles, mix them with the carrier gas to form aerosol bundles, and deliver them to the pneumatic focusing head through the aerosol delivery pipeline; Step 3: Inside the pneumatic focusing head, the sheath gas surrounds the aerosol bundle in the form of a ring flow field, performing preliminary coaxial physical compression on the aerosol particles, completing the initial pneumatic focusing, and forming a stable coaxial jet. Step 4: The jet enters the nozzle of the multi-stage lens, and the streamline is reconstructed by the structured flow field to improve the local flux, and the internal ultrasonic standing wave is superimposed to achieve non-contact ultimate convergence. Step 5: Under the protection of a steady fluid, and in conjunction with the movement of the motion platform, the particles are vertically stacked with a high degree of steepness.

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