Micro-nano metal structure electrofluid and electrochemical composite 3D printing method and device

Abstract

The invention discloses a micro-nano metal structure electrofluid and electrochemical composite 3D printing method and device.The printing method comprises the steps that a non-metal micro-nozzle injected with metal ion-nanoparticle mixed liquid serves as a printing tool, and a microwire electrode connected with the positive electrode of a voltage source is inserted into the metal ion-nanoparticle mixed liquid in the non-metal micro-nozzle in a suspended mode; connecting the substrate with the negative electrode of the voltage source; the voltage source applies an electric field between the microwire electrode and the base material, and the metal ion-nanoparticle mixed liquid is sprayed out in the form of ionic liquid drops wrapping metal particles under the action of traction force of the electric field and flies to the surface to be deposited of the base material at a high speed in the direction of an electric field line; under the synergistic effect of impact self-sintering of the metal nanoparticles and oxidation-reduction precipitation of the metal ions, layered forming of the metal micro-nano structure is achieved; layer-by-layer accumulation printing of the micro-nano scale complex three-dimensional metal structure is achieved by controlling the printing distance, and high-precision, high-strength, post-treatment-free, efficient and low-cost preparation of the multi-material array structure can be achieved.

Description

Technical Field

[0001] The present invention relates to the field of electrodeposition technology, and in particular to a micro-nano metal structure electrofluid and an electrochemical composite 3D printing method and device. Background Art

[0002] With the rapid development of microelectronics, biomedicine, bionic manufacturing and many other fields, the processing accuracy of 3D printed parts has reached the micron to nanometer level. However, due to the reduction of printing size, the limited types of printable materials and the complex post-processing process, its application in the manufacturing of complex multifunctional materials and structures is restricted.

[0003] A Chinese patent application with application number CN202011031924.X filed on September 27, 2020, discloses a preparation method for a silver filter element based on electrofluid printing. This method obtains nanosilver particle ink by evenly mixing a mixed solvent with silver nanoparticles, and uses electrofluid printing to print a silver grid on a base non-woven fabric with nanosilver sol, and then uses nitrogen and inert gas as an annealing and curing atmosphere to anneal and cure the non-woven fabric to obtain a silver filter element. This preparation method has a simple process and low cost, and can evenly deposit metal patterns so that nanosilver with metal bonds can be firmly bonded to a covalently bonded non-woven fabric substrate. However, this method is mainly aimed at the deposition of single particles and cannot be applied to the processing of other metal materials.

[0004] A Chinese patent application with application number CN202110769948.3 filed on November 2, 2021, discloses a laser ablation-electrospray printing method for micro-nano layered structures. This method uses a laser beam to generate local high temperature ablation on the pad to form micron-scale grooves, and under the guidance of a visual morphology detection module, a conductive ink is sprayed into the grooves to prepare a micro-nano layered structure. This processing method has the characteristics of simple process, short processing cycle, and wide material adaptability. However, this method does not take into account the thermal damage to the substrate caused by high-temperature ablation.

[0005] A Chinese patent application with application number CN202211318055.8 filed on October 26, 2022, discloses an electrofluidic additive manufacturing device and printing method for metal materials. The method proposes a combination of an annular electrode and a worktable electrode, a low-melting-point metal solution is configured, and an electrofluidic additive manufacturing device is used to form a conical jet to print a three-dimensional structure on the blank, and then the structure on the blank is sintered and solidified through post-processing sintering. This preparation method can print structures with higher resolution and produce a stable conical jet. However, this method relies on a low-melting-point metal solution, and high-melting-point metals cannot be processed by this method, which limits its scope of application.

[0006] A Chinese patent application numbered CN202110467238.5 filed on April 28, 2021, discloses a narrow-linewidth metal-type low-voltage varistor and a method for preparing it by electrofluid printing. This method uses an electrofluid to print nanosilver paste on a glass work surface to form a varistor, and solidifies the varistor by annealing to obtain a low-voltage metal varistor with a very narrow linewidth. The preparation method has a simple process, a low sintering temperature, and good microscopic uniformity. However, the varistor prepared by this method has a micro-nanoscale size. During the annealing process, thermal expansion or contraction may cause the shape of the device to deform, thereby affecting its performance.

[0007] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgement or any form of suggestion that the information constitutes the prior art already known to ordinary technicians in this field. Summary of the invention

[0008] Purpose of the invention: The technical problem to be solved by the present invention is to provide a method and device for electrofluidic and electrochemical composite 3D printing of micro-nano metal structures in view of the deficiencies of the prior art, so as to realize the integrated manufacturing of various functional materials and multi-scale complex structures, and combine ionic solvents and metal particles to realize low-cost, multi-element, high-resolution, and post-processing-free complex micro-nano structure 3D printing, thereby solving the problems of low resolution of micro-nano 3D printing, limited types of printable materials, and complex post-processing.

[0009] In order to solve the above technical problems, the first aspect of the present invention provides a micro-nano metal structure electrofluid and electrochemical composite 3D printing method, which includes: using a non-metallic micro-nozzle filled with a metal ion-nanoparticle mixture as a printing tool, inserting a micro-wire electrode connected to the positive electrode of a voltage source into the metal ion-nanoparticle mixture in the non-metallic micro-nozzle, and connecting a substrate to the negative electrode of the voltage source; the voltage source applies an electric field between the micro-wire electrode and the substrate, and the metal ion-nanoparticle mixture in the non-metallic micro-nozzle is ejected in the form of ion droplets wrapped around metal particles under the action of the electric field traction force and flies to the surface to be deposited of the substrate at high speed along the direction of the electric field line. Under the synergistic effect of kinetic energy and Joule heat, local high temperature is rapidly generated, so that the metal particles are quickly sintered and stacked. The ion droplet part that wraps the metal particles accumulates positive charges on its surface under the action of the electric field. When it flies to the surface of the workpiece with negative charge, an oxidation-reduction reaction occurs inside the droplet, and the metal element is precipitated at the contact position between the droplet and the workpiece. Under the synergistic effect of the metal nanoparticles' impact self-sintering and the metal ions' redox precipitation in the ionic droplets, the layered forming of the metal micro-nano structure is achieved; and the required layer-by-layer cumulative printing of the metal micro-nano structure is achieved by controlling the printing spacing.

[0010] In the invention, the droplets are driven by voltage. When the droplets contact the surface of the substrate, the current passes through the resistors in the metal particles. The resistance of the metal particles themselves converts electrical energy into thermal energy. When the heat reaches the sintering temperature of the metal particles, a neck is formed between the contact points of the metal particles, causing self-sintering and agglomeration between the metal particles.

[0011] The desired metal micro-nanostructure can be printed layer by layer by controlling the printing spacing, which means controlling the moving speed of the non-metallic micro-nozzle to match the thickness of the single-layer printing.

[0012] Furthermore, the types of the voltage include pulse voltage and constant voltage.

[0013] Specifically, the voltage is a periodic pulse voltage sequence, including a high-order pulse group and a low-order pulse group, the high-order pulse group and the low-order pulse group appear alternately and continuously, wherein the high-order pulse group is used to control the impact self-sintering of the metal nanoparticles, and the low-order pulse group is used to control the redox precipitation of the metal ions in the ionic droplets, and the ratio of the stacked metal particles in the workpiece to the reduced metal elements is adjusted by adjusting the amplitude of each high-order pulse in the high-order pulse group and the amplitude of each low-order pulse in the low-order pulse. The envelope of the periodic pulse voltage sequence is a square wave, a step wave, a sine wave or a triangle wave.

[0014] Specifically, the voltage is in a constant voltage mode, and the amplitude of the voltage is used to control the flight speed of the ionic droplets encapsulating the metal particles, the reduction rate of the metal ions in the ionic droplets, and the degree of particle sintering.

[0015] Specifically, the electric field, the printing spacing, the back pressure of the non-metallic micro-nozzle and the inner diameter of the nozzle are controlled to be constant, so as to realize the layer-by-layer cumulative printing of the three-dimensional metal micro-nano structure with equal cross-section. The three-dimensional metal micro-nano structure with equal cross-section is a micro-pillar array structure, a grid structure or a porous structure;

[0016] Alternatively, the intensity of the electric field and the printing spacing are changed in real time during the layered molding printing process to achieve layer-by-layer cumulative printing of a three-dimensional metal micro-nano structure with a variable cross-section; the three-dimensional metal micro-nano structure with a variable cross-section is a conical cross-section structure or an elliptical cross-section structure.

[0017] Specifically, the non-metallic micro-nozzle is a single-nozzle nozzle or a multi-nozzle nozzle for preparing array micro-nano structures;

[0018] Alternatively, the non-metallic micro-nozzle is a nozzle with adjustable nozzle shape and inner diameter, and the nozzle shape and inner diameter are dynamically changed during the printing process, thereby changing the volume and shape of the ion droplets ejected by the electric field traction force; the volume of the ion droplets determines the single-layer printing area formed after the ion droplets are spread out;

[0019] Alternatively, the non-metallic micro-nozzle is a multi-material nozzle, comprising two or more feed pipes for injecting different metal ion-nanoparticle mixtures and a nozzle connected to the two or more feed pipes.

[0020] Specifically, the printing spacing includes an initial printing spacing and a process printing spacing. The initial printing spacing determines the deposition position of the ion droplets on the surface to be deposited and is selected according to the inner diameter of the nozzle; the process printing spacing determines the distribution and intensity of the electric field. The distribution and intensity of the electric field are controlled by adjusting the process printing spacing so that the electric field can uniformly control the deposition trajectory of the ion droplets.

[0021] Specifically, the pressure and flow rate of the solution at the nozzle outlet are controlled by applying back pressure, thereby controlling the flow rate of the nozzle.

[0022] Specifically, the state of the ion droplets ejected by the traction force of the electric field is controlled by adjusting the intensity of the electric field. When the electric field is a strong electric field, the electric field pulls out a plurality of continuous droplets to form a droplet chain or a liquid column; when the electric field is a weak electric field, the electric field pulls a single and discontinuous droplet.

[0023] Furthermore, the metal ion-nanoparticle mixed solution also includes a low melting point sintering agent, and the low melting point sintering agent is selected from any one or a combination of two or more of a metal-based sintering agent, an inorganic compound sintering agent and an organic compound sintering agent.

[0024] In this embodiment, by adding a low melting point sintering agent to the solution, the reactivity of the particle surface can be changed, so that the sintering temperature required for the particles can be reduced. The sintering agent is mainly added during the solution preparation, and no post-processing addition is required.

[0025] The second aspect of the present invention provides a micro-nano metal structure electrofluid and electrochemical composite 3D printing device, the device comprising:

[0026] A substrate workbench for holding a substrate, wherein the substrate workbench can be translated along the Y direction;

[0027] A multi-nozzle system is located above the substrate workbench and can move along the Z-axis direction and the X-axis direction; the multi-nozzle system includes a plurality of mutually independent non-metallic micro-nozzles filled with a metal ion-nanoparticle mixture, and a micro-wire electrode is inserted into the metal ion-nanoparticle mixture inside each of the non-metallic micro-nozzles;

[0028] A micro-droplet dispensing device, wherein the cavity of each of the non-metallic micro-nozzles is connected to the micro-droplet dispensing device;

[0029] A voltage source, comprising a positive electrode and a negative electrode, wherein the positive electrode is electrically connected to the microwire electrode, and the negative electrode is electrically connected to the substrate, and is used to apply an electric field between the microwire electrode and the substrate;

[0030] A three-axis displacement system, connected to the substrate workbench and the multi-nozzle system, respectively, for driving the substrate workbench to move and driving the multi-nozzle system to move;

[0031] And a data acquisition system, the data acquisition system includes an illumination device, a high-speed camera, a back pressure control system, a temperature controller and a humidity controller; the high-speed camera is used to capture and analyze the flight state of the ionic droplets and the morphology of the micro-nano structure in real time under the illumination of the illumination device; the back pressure control system includes a pneumatic adjustment device, a control system, a gas pipeline and a pressure sensor, the gas is transmitted to the non-metallic micro-nozzle through the gas pipeline to apply back pressure to control the pressure of the solution in the non-metallic micro-nozzle; the pneumatic adjustment device is installed on the gas pipeline to adjust the gas pressure; the pressure sensor is installed at the nozzle outlet of the non-metallic micro-nozzle to monitor the pressure at the nozzle outlet of the non-metallic micro-nozzle in real time; the control system is configured to adjust the pneumatic adjustment device according to the detection data of the pressure sensor; the temperature controller and the humidity controller are used to measure and regulate the printing temperature and humidity respectively;

[0032] The metal ion-nanoparticle mixture in the non-metallic micro-nozzle is ejected in the form of ion droplets encapsulating metal particles under the action of the electric field traction force and flies at high speed along the direction of the electric field lines to the surface to be deposited on the substrate. The substrate workbench and the multi-nozzle system are driven to move relative to each other through the three-axis displacement system, and the required three-dimensional metal micro-nano structure is prepared on the surface to be deposited by controlling the electric field.

[0033] Beneficial effects:

[0034] 1. The present invention adopts a micro-nano metal structure electrofluid and electrochemical composite 3D printing method, and realizes the multi-element integrated manufacturing of complex metal structures at the micro-nano scale under the synergistic effect of electrofluid metal particle self-sintering and electrochemical oxidation-reduction. On the one hand, this method uses electrofluid self-sintering to promote the rapid fusion and stacking of metal particles through Joule heat, and on the other hand, it uses electrochemical oxidation-reduction to obtain the required solid metal through the precipitation of metal ions. Self-sintering can achieve rapid fusion of metal particles at a lower temperature, and electrochemistry can make the precipitated solid metal fill the particle pores generated during the self-sintering process. The two process methods complement each other to obtain a dense metal structure, and no additional high-temperature sintering or chemical treatment is required, which simplifies the process and reduces energy consumption and cost.

[0035] 2. The present invention adopts a micro-nano metal structure electrofluid and electrochemical composite 3D printing method. The printing voltage can be a pulse voltage. The periodic step transformation of high and low order pulses is used to accurately control the content of metal particles and ions in the traction droplets, thereby achieving precise control of the proportion of the components of the printed parts.

[0036] The printing voltage can also be in constant voltage mode. By adjusting the voltage amplitude, it can not only avoid the deviation caused by speed fluctuations during the flight of droplets, but also ensure the stability of the electrochemical redox reaction. At the same time, the constant voltage mode helps to reduce sintering defects such as pores, cracks and uneven surfaces caused by voltage fluctuations.

[0037] 3. The present invention adopts a micro-nano metal structure electrofluid and electrochemical composite 3D printing method to achieve printing of uniform cross-sectional structures and variable cross-sectional structures by controlling the electric field, printing spacing, back pressure and the inner diameter of the nozzle in the nozzle. There is no need to interrupt or replace materials and equipment during the printing process, providing a new solution for the manufacture of multifunctional and complex micro-nano structures.

[0038] 4. The present invention adopts a micro-nano metal structure electrofluid and electrochemical composite 3D printing method. The printing nozzle can be a dynamic nozzle, that is, a nozzle with adjustable nozzle shape and inner diameter. The diameter and cross-sectional shape of the nozzle can be flexibly adjusted during the printing process to achieve real-time dynamic printing of complex contours. The printing nozzle can also be a multi-nozzle nozzle, which can realize the preparation of array micro-nano structures and improve the printing speed; it can also be a multi-material nozzle for continuous printing of different materials.

[0039] 5. The present invention adopts a micro-nano metal structure electrofluid and electrochemical composite 3D printing method to control the pressure and flow rate of the solution at the nozzle outlet by increasing the back pressure, thereby accurately adjusting the flow rate of the nozzle. This method not only reduces the flow fluctuation caused by unstable air pressure, but also reduces the risk of nozzle clogging.

[0040] 6. The present invention adopts a micro-nano metal structure electrofluid and electrochemical composite 3D printing method, and controls the state of the traction droplet by the strength of the electric field. The strong electric field tractions multiple continuous droplets to form a droplet chain or liquid column, which is suitable for high-efficiency and large-area printing needs, while the weak electric field traction single and discontinuous droplets reduces the crosstalk between droplets, which is suitable for high-precision and high-resolution printing needs. This control method helps to achieve the best printing effect in different printing tasks.

[0041] 7. The present invention adopts a micro-nano metal structure electrofluid and electrochemical composite 3D printing method, adds a low melting point sintering agent to the solution, and changes the melting point of the particles by adjusting the content of the sintering agent, thereby ensuring that the particles achieve an ideal sintering effect within a specified temperature range. This method optimizes the integrity of the printed structure and avoids the performance degradation of the printed parts due to uneven sintering.

[0042] 8. The present invention adopts a micro-nano metal structure electrofluid and electrochemical composite 3D printing method. Compared with other printing machines, the 3D printing machine bed used in this method combines a high-speed camera for real-time monitoring, a multi-material distribution system of a multi-nozzle system, a back pressure control system for droplet stability control, and environmental regulation of temperature and humidity. The comprehensive application of these technologies not only improves the printing quality, but also enhances its accuracy and stability in manufacturing complex micro-nano structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0044] Figure 1 It is a schematic diagram of the principle of electrochemical 3D printing based on self-sintering of metal nanoparticles provided in the embodiments of the present invention;

[0045] Figure 2 It is a schematic diagram of the electric field waveform of the micro-nano metal structure electrofluid and electrochemical composite 3D printing method provided in the embodiment of the present invention, and the envelope of the voltage is a square wave;

[0046] Figure 3 It is a schematic diagram of the electric field waveform of the micro-nano metal structure electrofluid and electrochemical composite 3D printing method provided in the embodiment of the present invention;

[0047] Figure 4 Schematic diagram of variable cross-section printing of micro-nano metal structure electrofluid and electrochemical composite 3D printing method provided in the embodiment of the present invention;

[0048] Figure 5 It is a schematic diagram of a dynamic single nozzle of a micro-nano metal structure electrofluid and electrochemical composite 3D printing method provided in the embodiment of the present invention;

[0049] Figure 6 It is a schematic diagram of multi-nozzle array printing of a micro-nano metal structure electrofluid and electrochemical composite 3D printing method provided in the embodiment of the present invention;

[0050] Figure 7 It is a schematic diagram of single nozzle multi-material printing of the micro-nano metal structure electrofluid and electrochemical composite 3D printing method provided in the embodiment of the present invention;

[0051] Figure 8 Schematic diagram of the back pressure system of the micro-nano metal structure electrofluid and electrochemical composite 3D printing method provided in the embodiments of the present invention;

[0052] Fig. 9It is a schematic diagram of the micro-pillar array structure of the micro-nano metal structure electrofluid and electrochemical composite 3D printing method provided in the embodiment of the present invention;

[0053] Fig.10 It is a schematic diagram of a honeycomb structure of a micro-nano metal structure electrofluid and an electrochemical composite 3D printing method provided in the embodiments of the present invention;

[0054] Fig.11 It is a schematic diagram of the grid structure of the micro-nano metal structure electrofluid and electrochemical composite 3D printing method provided in the embodiment of the present invention;

[0055] Fig.12 It is a schematic diagram of the heat sink structure of the micro-nano metal structure electrofluid and electrochemical composite 3D printing method provided in the embodiment of the present invention;

[0056] Fig.13 It is a schematic diagram of a variable cross-section layered structure of a micro-nano metal structure electrofluid and an electrochemical composite 3D printing method provided in the embodiments of the present invention;

[0057] Fig.14 Schematic diagram of the self-sintering of metal particles by electric current Joule heat in the electrofluidic and electrochemical composite 3D printing method of micro-nano metal structure provided in the embodiments of the present invention;

[0058] Fig.15 It is a schematic diagram of an electrochemical 3D printing device based on metal nanoparticle self-sintering electrofluid provided in the examples of the present invention.

[0059] The description of the accompanying drawings is:

[0060] 1. Base; 3. Work surface; 4. Support frame; 5. Voltage source; 6. High-speed camera; 7. Articulator 8. Connecting plate; 9. Back pressure control system; 10. High-speed camera fixing plate; 11. Z feed axis support plate; 12. Z feed axis; 13. Non-metallic micro nozzle; 14. Microwire electrode; 15. X feed axis; 17. Temperature controller; 18. Humidity controller; 19. Micro droplet dispensing device; 20. Illuminating device; 21. Substrate; 22. Substrate workbench; 23. Y feed axis; 25. Nozzle fixing plate; 26. Conduit; 27. Nozzle; 28. Cavity; 29. ​​Feed pipe; 30. Nozzle head; 31. Gasket; 32. Bolt; 33. Pin; 34. Nozzle cavity; 36. Pneumatic adjustment device; 35. Control system; 37. Gas pipeline; 38. Three-dimensional metal micro-nano structure. DETAILED DESCRIPTION

[0061] The present invention discloses a method and device for electrofluidic and electrochemical composite 3D printing of micro-nano metal structures. The present invention can be applied to the integrated manufacturing of micro-nano scale multiple functional materials and multi-scale complex structures in the fields of aerospace, flexible electronic devices, biomedicine, micro-nano electromechanical systems, etc. Under the synergistic effect of electrofluidic metal particle self-sintering and electrochemical redox, multi-element integrated manufacturing of micro-nano scale complex metal structures is realized. At the same time, the solid metal generated during the reduction process is used to fill the tiny gaps between the sintered particles, and finally the high-precision, low-porosity and high-conductivity processing of three-dimensional metal micro-nano structures is realized.

[0062] The first aspect of the present invention discloses a micro-nano metal structure electrofluid and electrochemical composite 3D printing method, the 3D printing method comprising:

[0063] like Figure 1 As shown, a non-metallic micro-nozzle 13 filled with a metal ion-nanoparticle mixture is used as a printing tool, a micro-wire electrode 14 connected to the positive electrode of a voltage source 5 is suspended and inserted into the metal ion-nanoparticle mixture in the non-metallic micro-nozzle 13, and a substrate 21 is connected to the negative electrode of the voltage source 5. The voltage source 5 applies a voltage between the micro-wire electrode 14 and the substrate 21 to form a strong electric field, and the metal ion-nanoparticle mixture in the non-metallic micro-nozzle 13 is pulled out in the form of ion droplets encapsulating metal particles under the action of the electric field traction force and flies at high speed along the direction of the electric field lines toward the surface to be deposited of the substrate 21, and under the action of the electric field, the surface of the ion droplets encapsulating metal particles is accumulated with positive charges. When the ion droplets encapsulating the metal particles fly to the surface to be deposited and collide with it, the metal particles quickly generate local high temperatures under the synergistic effect of kinetic energy and Joule heat, resulting in rapid self-sintering and stacking at the contact position between the ion droplets and the surface to be deposited. The metal ions in the ion droplets undergo redox reactions under the action of the electric field, and the reduced metal elements precipitate at the contact position between the ion droplets and the surface to be deposited and fill the particle pores generated during the self-sintering process. Under the synergistic effect of the self-sintering of metal nanoparticles and the redox precipitation of metal ions in the ion droplets, the layered forming of metal micro-nano structures is achieved. The required three-dimensional metal micro-nano structures can be printed layer by layer by controlling the printing spacing.

[0064] Among them, the electric field strength is: the minimum electric field strength is 10 6 V / m, which is sufficient to overcome the surface tension and viscosity of the mixed liquid.

[0065] In the present application, the non-metallic micro-nozzle 13 refers to a nozzle using a micro-nozzle, which is used to prepare a micro-structure with a structural scale of several hundred nm to several um.

[0066] The printing method of the present invention can realize the multi-element integrated manufacturing of complex structures at the micro-nano scale by integrating multiple functional materials and utilizing the synergistic effect of ionic solvents and metal particles. The method drives the functional materials in the solution, namely metal ions and metal particles, to form the desired structure under the traction of the electric field through the precise control of the composite voltage. The self-sintering mechanism is utilized to enable the metal particles in the printing process to be sintered in situ at low temperature. The solid metal precipitated by electrochemical means fills the particle pores generated during the self-sintering process to form a micro-nano structure with high strength and high conductivity. This process does not require additional high-temperature treatment or complex post-processing steps, simplifies the manufacturing process, and improves production efficiency and material utilization.

[0067] It should be understood that before printing, it is necessary to prepare a metal ion-nanoparticle mixture and select a voltage in advance. Specifically, the step of preparing a metal ion-nanoparticle mixture includes: preparing a metal ion solution by dissolving a metal salt in deionized water. After the metal ion solution is prepared, the selected metal nanoparticles are placed in the metal ion solution, and a dispersant is placed to perform magnetic stirring to make it evenly dispersed, followed by ultrasonic treatment to ensure that the metal ions are fully in contact with the metal nanoparticles. The selection of metal nanoparticles is usually determined based on the physical and chemical properties of the desired structure and the printing accuracy requirements. More specifically, the selected metal nanoparticles can be gold nanoparticles, silver nanoparticles, copper nanoparticles, platinum nanoparticles or other metal conductive nanoparticles, and the dispersant is any one or a combination of two or more of a surfactant, a polymer dispersant, a small molecule organic dispersant and an inorganic dispersant.

[0068] Furthermore, in order to ensure a good deposition effect, the surface to be deposited of the substrate 21 can be pretreated before work, including the following steps: grinding the surface to be deposited with sandpaper, and then using a polishing machine for fine polishing and ultra-fine polishing to make the surface to be deposited reach a mirror effect, and after removing scratches, put it in anhydrous ethanol for ultrasonic cleaning, remove surface stains and dust layers, and then dry and let it stand.

[0069] Furthermore, in order to increase the reaction rate of the microwire electrode during the deposition process, before working, the microwire electrode 14 is placed in a weakly acidic solution for etching to increase the surface activity of the microwire electrode 14, and then rinsed with deionized water to remove pollutants on the electrode surface.

[0070] Specifically, the voltage may be a periodic pulse voltage sequence or a constant voltage mode.

[0071] In one embodiment of the voltage, the voltage is a periodic pulse voltage sequence, including a high-order pulse group and a low-order pulse group, which appear alternately and continuously, wherein the high-order pulse group is used to control the impact self-sintering of metal nanoparticles, and the low-order pulse group is used to control the redox precipitation of metal ions in ionic droplets, and the ratio of the stacked metal particles and the reduced metal elements in the workpiece is adjusted by adjusting the amplitude of each high-order pulse in the high-order pulse group and the amplitude of each low-order pulse in the low-order pulse. The envelope of the periodic pulse voltage sequence is a square wave, a step wave, a sine wave or a triangle wave.

[0072] In the present application, the amplitude of the high-order pulse ranges from 0.08 kV to 3 kV, and the amplitude of the low-order pulse ranges from 0 kV to 0.08 kV.

[0073] In one embodiment, the periodic pulse voltage sequence is a periodic high-low order composite pulse. Figure 2 A high-low order composite pulse voltage includes a high-order pulse group with M high-order pulse voltages and a low-order pulse group with N low-order pulse voltages, M and N can be 1 or any other natural number, and the values ​​of M and N can be the same or different. The waveforms of the high-order pulse voltage and the low-order pulse voltage are both square waves, where V 高阶电压 is the high-order pulse voltage amplitude, V 低阶电压 is the low-order pulse voltage amplitude, t 开1 is the opening period of a single high-order pulse voltage, that is, the time interval from the rising edge to the falling edge of the high-order pulse voltage. This time interval is crucial because the rapid establishment of the high-order pulse voltage can effectively promote the ejection of ion droplets containing metal particles; t 关1 is the off period of a single high-order pulse voltage, that is, the time interval from the falling edge of the high-order pulse voltage to the rising edge of the next high-order pulse voltage; t 开2 is the opening period of a single low-order pulse voltage, that is, the time interval from the rising edge to the falling edge of the low-order pulse voltage, which directly affects the precise traction of the droplet and the printing quality; t 关2 is the off period of a single low-order pulse voltage, that is, the time interval from the falling edge of the low-order pulse voltage to the rising edge of the next low-order pulse voltage; t 开1 It can be 15μs-30μs, t 关1 and t 关2 Can be 5μs-10μs, t 开2 It can be 35μs-90μs. The opening period of a single low-level voltage t 开2 It should last longer to ensure that the droplets can be printed smoothly and accurately positioned.

[0074] In this embodiment, a high-order pulse group and a low-order pulse group appear alternately and continuously. At this time, the time interval from the falling edge of the last high-order pulse voltage in the high-order pulse group to the rising edge of the first low-order pulse voltage in the low-order pulse group following the high-order pulse group is equal to t 关1 The time interval from the falling edge of the last low-order pulse voltage in the low-order pulse group to the rising edge of the first high-order pulse voltage in the high-order pulse group following the low high-order pulse group is equal to t 关2 Correspondingly, one cycle T of the periodic high-low order composite pulse is composed of the opening period t of M high-order pulse voltages. 开1、 The off period t of M high-order pulse voltages 关1 , the opening period t of N low-order pulse voltages 开2 and the off period t of N low-order pulse voltages 关2 composition.

[0075] The high-order pulse voltage amplitude V in the periodic high-low order composite pulse 高阶电压 , low-order pulse voltage amplitude V 低阶电压 , the opening period t of a single high-order pulse voltage 开1、 The off period t of a single high-order pulse voltage 关1 , the opening period t of a single low-order pulse voltage 开2 and the off period t of a single low-order pulse voltage 关2 These parameters are all controllable and adjustable.

[0076] In another embodiment, see Figure 3 , the envelope of a pulse voltage sequence is in a shape that decreases first and then increases, such as a triangle wave and a sine wave. Specifically, the maximum value of the envelope is U max , the minimum value is U min The pulse width of each pulse voltage in the pulse voltage sequence, the interval time between two adjacent pulse voltages, and the maximum value and the minimum value of the envelope of the pulse voltage sequence are all controllable and adjustable.

[0077] In another embodiment of the voltage, the voltage is in a constant voltage mode, and the voltage amplitude is used to control the flight speed of the ionic droplets encapsulating the metal particles, the reduction rate of the metal ions in the ionic droplets, and the degree of particle sintering.

[0078] See now Figure 4 By combining the constant-section and variable-section printing technologies, high-precision printing of complex structures such as pointed cones or bridges can be achieved.

[0079] Specifically, by controlling the electric field, printing spacing, back pressure of the non-metallic micro-nozzle 13 and the inner diameter of the nozzle to be constant, the layer-by-layer cumulative printing of the three-dimensional metal micro-nanostructure with equal cross-section can be achieved. The inner diameter of the nozzle here refers to the inner diameter of the nozzle in the non-metallic micro-nozzle 13. Figures 9 to 12As shown, the three-dimensional metal micro-nano structures 38 with equal cross-sections are respectively micro-pillar array structures, grid structures or porous structures. Figure 3 As shown, by changing the intensity of the electric field and the printing spacing in real time during the layered molding printing process, the three-dimensional metal micro-nano structure 38 with a variable cross-section can be printed layer by layer. The three-dimensional metal micro-nano structure 38 with a variable cross-section is a conical cross-section structure or an elliptical cross-section structure. Fig.13 As shown, a layered structure of variable cross-section printing is shown. By dynamically changing the cross-sectional shape and size of each layer, the printed structure has a cross-section that changes layer by layer.

[0080] The back pressure refers to the reverse pressure applied to the liquid in the non-metallic micro nozzle 13 to balance the electric field force, adjust the flow rate of the liquid, and prevent the liquid from flowing out of the nozzle too quickly. At the same time, the back pressure can also effectively prevent the formation of bubbles in the liquid, ensuring the uniformity of the droplets and the stability of the injection process.

[0081] Specifically, the non-metallic micro nozzle 13 can be a single nozzle or a multi-nozzle nozzle. The nozzle of any of the above nozzles can also be adjustable in shape and inner diameter.

[0082] See now Figure 5 The non-metallic micro-nozzle 13 is a nozzle with adjustable nozzle shape and inner diameter, including a nozzle cavity 34 for caching a metal ion-nanoparticle mixture, a nozzle head 30, a gasket 31 and a pin 33. The nozzle head 30 is connected to the bottom of the nozzle cavity 34 and communicated with the nozzle cavity 34. A nozzle is provided at the bottom of the nozzle head 30 to eject droplets pulled by the power field. A plurality of gaskets 31 are provided and a plurality of gaskets 31 are arranged at intervals around the nozzle of the nozzle head 30. Each gasket 31 is respectively provided with a pin 33, and the pin 33 is connected to the corresponding gasket 31 by a bolt 32 to form the vertex of the nozzle polygon of the nozzle head 30. The nozzle head 30 is made of silicone rubber material. When the pin 33 is connected to an external drive system, the drive system moves by driving the pin 33, and these pins form the vertex of the nozzle outlet polygon, which can flexibly change the nozzle diameter and cross-sectional shape according to different material requirements and geometric shapes during the printing process. This dynamic adjustment not only significantly improves the printing accuracy, but also adapts to the printing of complex structures. In a specific embodiment, see Figure 5 , the number of pins 33 is 8. The realization of a nozzle with adjustable nozzle shape and inner diameter belongs to the prior art and is not the main invention of this application, and therefore, it will not be described in detail in this application.

[0083] Since the inner diameter of the nozzle determines the volume of the ion droplets ejected by the electric field traction force, and the volume of the ion droplets determines the single-layer printing area formed after the ion droplets spread out, before use, a suitable nozzle inner diameter can be selected according to the single-layer printing area. In a specific embodiment, when the single-layer printing area is less than 0.5 μm2 When the single-layer printing area is larger than 0.5 μm, a nozzle with a nanometer inner diameter is selected. 2 When spraying, choose a nozzle with an inner diameter of micron level.

[0084] See now Figure 6 , Figure 6 The non-metallic micro nozzle 13 shown is a multi-nozzle nozzle, including a cavity 28 for caching a metal ion-nanoparticle mixture, a feed pipe 29, a nozzle 27 and a conduit 26. A feed pipe 29 is connected to the upper part of the cavity 28, and the wall of the feed pipe 29 is connected to the conduit 26. The conduit 26 is connected to the inside of the cavity 28 through the feed pipe 29, and the conduit 26 serves as an inlet for the microwire electrode 14 to be inserted into the cavity 28. There are multiple nozzles 27, and the multiple nozzles 27 are respectively installed at the bottom of the cavity 28 and are connected to the inside of the nozzle cavity 34 to realize synchronous printing of a multi-nozzle array. The multi-nozzle nozzle can be used for the efficient preparation of micro-nano structures and can ensure the synchronization and coordination between the nozzles.

[0085] See now Figure 7 , Figure 7 The non-metallic micro nozzle 13 shown is a multi-material nozzle, which is different from Figure 5 The multi-nozzle nozzle shown in the figure has three feed pipes 29 in the multi-material nozzle, and each feed pipe 29 is connected to the cavity 28 of the multi-material nozzle. Each feed pipe 29 can provide a different metal ion-nanoparticle mixture. By providing three feed pipes 29, the nozzle has the ability to print multiple materials, adapt to complex functional requirements, and is particularly suitable for printing multi-layered, multi-metal component composite structures.

[0086] It should be understood that Figure 7 The multi-material nozzle shown is provided with three feed pipes 29, the number of which is not limited to three and can be increased or decreased according to actual needs; Figure 7 The multi-material nozzle shown has only a single nozzle 27 disposed at the bottom of the cavity 28, but multiple nozzles 27 may also be disposed at the bottom of the cavity 28 to achieve synchronous printing of a multi-nozzle array.

[0087] Specifically, the substrate 21 can be a metal, a semiconductor or a non-metal workpiece. More specifically, the metal material can be a metal material with good thermal conductivity and electrical conductivity, such as copper, aluminum, silver and gold, which are suitable for printing sensors and conductive circuits. Semiconductor materials include silicon, gallium arsenide, silicon carbide, etc., which are suitable for the manufacture of transistors and optoelectronic devices. Non-metallic materials include glass, ceramics, polymers and paper, which are widely used in microfluidic chips, flexible displays and packaging materials, etc., and can provide good mechanical, optical and chemical properties.

[0088] It should be understood that when the substrate 21 is a non-metallic workpiece, a conductive layer can be coated on the surface to be deposited or an external electric field can be applied to generate induced charges on the workpiece surface. Even if the workpiece itself is not conductive, the workpiece surface can still be charged by electric field induction.

[0089] Specifically, the printing spacing includes the initial printing spacing and the process printing spacing. The initial printing spacing refers to the distance between the nozzle outlet and the surface to be deposited before the first printing. It determines the deposition position of the ion droplets on the surface to be deposited and is selected according to the inner diameter of the nozzle. The process printing spacing refers to the distance between the nozzle outlet and the top of the printed metal micro-nano structure during the printing process. It determines the distribution and intensity of the electric field. The distribution and intensity of the electric field are controlled by adjusting the process printing spacing so that the electric field can uniformly control the deposition trajectory of the ion droplets.

[0090] Specifically, the flow rate and spray angle of the nozzle are controlled by controlling the pressure and flow rate of the solution at the nozzle outlet. Figure 8 The pressure and flow rate of the solution at the nozzle outlet of the non-metallic micro nozzle 13 are controlled by a back pressure control system. The pressure and flow rate of the solution at the nozzle outlet are adjusted by the back pressure control system to control the flow rate and injection angle of the nozzle. The back pressure control system 9 may include a pneumatic regulating device 36, a control system 35, a gas pipeline 37, and a pressure sensor. Figure 8 The pressure sensor is not shown. Gas, such as air, is transmitted to the non-metallic micro-nozzle 13 through the gas pipeline 37, thereby applying back pressure to control the pressure of the solution in the non-metallic micro-nozzle 13. The pneumatic regulating device 36 is installed on the gas pipeline 37 for regulating the gas pressure. The pressure sensor is installed on the non-metallic micro-nozzle 13 for real-time monitoring of the pressure at the nozzle outlet of the non-metallic micro-nozzle 13. The control system 35 is configured to adjust the pneumatic regulating device 36 according to the detection data of the pressure sensor to ensure that the internal pressure of the non-metallic micro-nozzle 13 remains within a set range.

[0091] By adjusting the back pressure, the non-metallic micro nozzle 13 can spray solutions of different viscosities. A high-viscosity solution uses a higher back pressure to overcome a larger flow resistance, and a low-viscosity solution uses a lower back pressure to improve spray stability. Stable back pressure control can not only ensure the stability of the spraying process, but also improve the printing quality, so that the sprayed droplets have better positioning and morphology control, thereby improving the overall printing effect and accuracy.

[0092] In the present application, the nozzle outlet refers to the nozzle outlet on the nozzle.

[0093] Specifically, the state of the ion droplets ejected by the electric field traction force is controlled by adjusting the intensity of the electric field. When the electric field is a strong electric field, the electric field pulls out multiple continuous droplets to form a droplet chain or liquid column to achieve large-area rapid printing. When the electric field is a weak electric field, the electric field pulls a single and discontinuous droplet to achieve high-precision printing.

[0094] Furthermore, the metal ion-nanoparticle mixture also includes a low melting point sintering agent, and the low melting point sintering agent is selected from any one or a combination of two or more of a metal-based sintering agent, an inorganic compound sintering agent and an organic compound sintering agent.

[0095] like Fig.14 As shown in the figure, metal particles produce a self-sintering effect by applying high voltage and adding sintering agents. When current passes through the particles, the resistance inside the particles will generate Joule heat, the local temperature will rise, and the particle sintering will be promoted. The role of the sintering agent is to remove the organic coating layer on the surface of the metal particles, reduce the sintering temperature of the particles, and allow the sintering process to be carried out at a lower temperature, which helps to reduce thermal damage to the processed structure.

[0096] like Fig.15 As shown, the second aspect of the present invention discloses a micro-nano metal structure electrofluid and electrochemical composite 3D printing device, which includes a substrate workbench 22 for holding a substrate 21, a multi-nozzle system, a micro-droplet dispensing device 19, a voltage source 5 and a three-axis displacement system. The substrate workbench 22 can be translated along the Y direction. The multi-nozzle system is located above the substrate workbench 22 and can move along the Z-axis direction and the X-axis direction. It includes more than one independent non-metallic micro-nozzles 13 filled with a metal ion-nanoparticle mixture, and the metal ion-nanoparticle mixture inside each non-metallic micro-nozzle 13 is respectively extended with a micro-wire electrode 14. The cavity of each non-metallic micro-nozzle 13 is connected to the micro-droplet dispensing device 19. The micro-droplet dispensing device 19 is used to achieve accurate distribution of multiple droplet materials during the printing process, and also allows micro-nano structures with different characteristics to be manufactured simultaneously on the surface of the workpiece. The voltage source 5 includes a positive electrode and a negative electrode, the positive electrode is electrically connected to the microwire electrode 14, and the negative electrode is electrically connected to the substrate 21, and is used to apply an electric field between the microwire electrode 14 and the substrate 21. The substrate workbench 22 and the multi-nozzle system are respectively connected to the three-axis displacement system, and the three-axis displacement system is used to drive the substrate workbench 22 to move, and drive the multi-nozzle system to move.

[0097] When the voltage source 5 applies an electric voltage between the microwire electrode 14 and the substrate 21 to form a strong electric field, the metal ion-nanoparticle mixture in the non-metallic micronozzle 13 is ejected in the form of ion droplets wrapping the metal particles under the action of the electric field traction force and flies at high speed along the direction of the electric field lines to the surface to be deposited of the substrate 21. The substrate workbench 22 and the multi-nozzle system are driven to move relative to each other through the three-axis displacement system, and the electric field is controlled to achieve the preparation of the required three-dimensional metal micro-nano structure on the surface to be deposited.

[0098] It should be understood that the non-metallic micro-nozzle 13 can be a multi-material nozzle. Since the multi-material nozzle has multiple feed pipes, it can continuously achieve accurate distribution of multiple droplet materials. Further, the non-metallic micro-nozzle 13 can be a multi-nozzle nozzle or a single-nozzle nozzle.

[0099] Optionally, the substrate workbench 22 can be used as an auxiliary electrode. Specifically, the substrate workbench 22 is connected to the negative electrode of the voltage source 5, and the negative electrode of the voltage source 5 is electrically connected to the substrate 21 through the substrate workbench 22, thereby achieving electrical connection between the negative electrode and the substrate 21.

[0100] For details, see Fig.15 The three-axis displacement system includes a base 1, an X feed axis 15, a Y feed axis 23, a Z feed axis 12, a Z feed axis support plate 11, a support frame 4, a connecting plate 8 and a nozzle fixing plate 25. The base 1 has a work surface 3, and the work surface 3 can provide a solid support foundation. The work surface 3 is connected to the Y feed axis 23, and the Y feed axis 23 can move along the Y direction relative to the work surface 3. The top of the Y feed axis 23 is connected to the substrate workbench 22 so that the substrate workbench 22 moves synchronously with it. The support frame 4 is located at the rear side of the Y feed axis 23 and is fixedly connected to the base 1. The Z feed axis 12 is installed on the support frame 4 through the Z feed axis support plate 11 and can move along the Z axis relative to the support frame 4. The X feed axis 15 is installed on the Z feed axis and can move along the X axis relative to the Z feed axis. The connecting plate 8 is fixedly connected to the X feed axis 15, and the nozzle fixing plate 25 for installing the multi-nozzle system is fixedly connected to the connecting plate 8.

[0101] For further information, see Fig.15 The device also includes a lighting device 20, a high-speed camera 6, a back pressure control system 9, a high-speed camera fixing plate 10, a temperature controller 17 and a humidity controller 18.

[0102] The high-speed camera 6 is used to capture and analyze the flight state of the ion droplets and the morphology of the micro-nano structure during the printing process and after the printing in real time under the illumination of the illumination device 20. By capturing the details of the pattern stacking process with the high-speed camera, the printing device can make necessary adjustments and optimizations. More specifically, the high-speed camera 6 is fixed to the hinge 7 through the high-speed camera fixing plate 10, and the hinge 7 is connected to the connecting plate 8. The high-speed camera 6 can rotate at multiple angles through the hinge 7.

[0103] See also Figure 3 , the back pressure control system 9 includes a pneumatic regulating device 36, a control system 35, a gas pipeline 37 and a pressure sensor. The gas is transmitted to the non-metallic micro-nozzle 13 through the gas pipeline 37, thereby applying back pressure to control the pressure of the solution in the non-metallic micro-nozzle 13. The pneumatic regulating device 36 is installed on the gas pipeline 37 to adjust the gas pressure. The pressure sensor is installed at the nozzle outlet of the non-metallic micro-nozzle 13 to monitor the pressure at the nozzle outlet of the non-metallic micro-nozzle 13 in real time. The control system 35 is configured to adjust the pneumatic regulating device 36 according to the detection data of the pressure sensor to ensure that the pressure in the non-metallic micro-nozzle 13 is maintained within a set range, thereby ensuring that the formation and release process of the droplets are always stable.

[0104] The temperature controller 17 and the humidity controller 18 are used to measure and regulate the printing temperature and humidity respectively, so as to ensure the stability of the printing environment and effectively reduce the printing quality problems caused by environmental changes.

[0105] Specifically, the lighting device 20 may be a lighting lamp, which may be connected to the connecting plate 8 by bolt fasteners, so as to ensure that the high-speed camera 6 can capture the clearest image under various light conditions.

[0106] The present invention provides a method and idea for a micro-nano metal structure electrofluid and electrochemical composite 3D printing method and device. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention. All components not specified in this embodiment can be implemented using existing technologies.

Claims

1. A micro-nano metal structure electrofluid and electrochemical composite 3D printing method, characterized in that: include: A non-metallic micro-nozzle (13) filled with a metal ion-nanoparticle mixture is used as a printing tool, a micro-wire electrode (14) connected to the positive electrode of a voltage source (5) is suspended and inserted into the metal ion-nanoparticle mixture in the non-metallic micro-nozzle (13), and a substrate (21) is connected to the negative electrode of the voltage source (5); the voltage source applies an electric field between the micro-wire electrode (14) and the substrate (21), and the metal ion-nanoparticle mixture in the non-metallic micro-nozzle (13) is ejected in the form of ion droplets encapsulating metal particles under the action of the electric field traction force and flies at high speed along the direction of the electric field line to the surface to be deposited of the substrate (21), and the layered molding of the metal micro-nano structure is achieved under the synergistic effect of the collision self-sintering of the metal nanoparticles and the oxidation-reduction precipitation of the metal ions in the ion droplets; and the required layer-by-layer cumulative printing of the metal micro-nano structure is achieved by controlling the printing spacing.

2. The micro-nano metal structure electrofluid and electrochemical composite 3D printing method according to claim 1, characterized in that: The voltage is a periodic pulse voltage sequence, including a high-order pulse group and a low-order pulse group, the high-order pulse group and the low-order pulse group appear alternately and continuously, wherein the high-order pulse group is used to control the impact self-sintering of the metal nanoparticles, and the low-order pulse group is used to control the redox precipitation of metal ions in the ionic droplets, and the ratio of the stacked metal particles in the workpiece and the metal elements obtained by the reduction is adjusted by adjusting the amplitude of each high-order pulse in the high-order pulse group and the amplitude of each low-order pulse in the low-order pulse; the envelope of the periodic pulse voltage sequence is a square wave, a step wave, a sine wave or a triangle wave.

3. The micro-nano metal structure electrofluid and electrochemical composite 3D printing method according to claim 1, characterized in that: The voltage is in a constant voltage mode, and the voltage amplitude is used to control the flight speed of the ionic droplets encapsulating the metal particles, the reduction rate of the metal ions in the ionic droplets, and the degree of particle sintering.

4. The micro-nano metal structure electrofluid and electrochemical composite 3D printing method according to claim 1, characterized in that: By controlling the electric field, the printing spacing, the back pressure of the non-metallic micro-nozzle (13) and the inner diameter of the nozzle to be constant, layer-by-layer cumulative printing of a three-dimensional metal micro-nano structure with a constant cross-section is achieved; The three-dimensional metal micro-nano structure with a uniform cross-section is a micro-pillar array structure, a grid structure or a porous structure; Alternatively, the intensity of the electric field and the printing spacing are changed in real time during the layered molding printing process to achieve layer-by-layer cumulative printing of a three-dimensional metal micro-nano structure with a variable cross-section; The three-dimensional metal micro-nano structure with variable cross-section is a conical cross-section structure or an elliptical cross-section structure.

5. The micro-nano metal structure electrofluid and electrochemical composite 3D printing method according to claim 1, characterized in that: The non-metallic micro-nozzle (13) is a single-nozzle nozzle or a multi-nozzle nozzle for preparing an array micro-nano structure; Alternatively, the non-metallic micro-nozzle (13) is a nozzle with an adjustable nozzle shape and inner diameter, and the nozzle shape and inner diameter are dynamically changed during the printing process, thereby changing the volume and shape of the ion droplets ejected by the electric field traction force; the volume of the ion droplets determines the single-layer printing area formed after the ion droplets are spread out; Alternatively, the non-metallic micro-nozzle (13) is a multi-material nozzle, comprising two or more feed pipes (28) for injecting different metal ion-nanoparticle mixtures and a nozzle (27) connected to the two or more feed pipes (28).

6. The micro-nano metal structure electrofluid and electrochemical composite 3D printing method according to claim 1, characterized in that: The printing spacing includes an initial printing spacing and a process printing spacing. The initial printing spacing determines the deposition position of the ion droplets on the surface to be deposited and is selected according to the inner diameter of the nozzle; the process printing spacing determines the distribution and intensity of the electric field. The distribution and intensity of the electric field are controlled by adjusting the process printing spacing so that the electric field can uniformly control the deposition trajectory of the ion droplets.

7. The micro-nano metal structure electrofluid and electrochemical composite 3D printing method according to claim 4, characterized in that: The flow rate of the nozzle is controlled by applying back pressure to control the pressure and flow rate of the solution at the nozzle outlet.

8. The micro-nano metal structure electrofluid and electrochemical composite 3D printing method according to claim 1, characterized in that: The state of the ion droplets ejected by the traction force of the electric field is controlled by adjusting the intensity of the electric field. When the electric field is a strong electric field, the electric field pulls out a plurality of continuous droplets to form a droplet chain or a liquid column; when the electric field is a weak electric field, the electric field pulls out a single and discontinuous droplet.

9. The micro-nano metal structure electrofluid and electrochemical composite 3D printing method according to claim 1, characterized in that: The metal ion-nanoparticle mixed solution further includes a low melting point sintering agent, and the low melting point sintering agent is selected from any one or a combination of two or more of a metal-based sintering agent, an inorganic compound sintering agent and an organic compound sintering agent.

10. A micro-nano metal structure electrofluid and electrochemical composite 3D printing device, characterized in that: include: A substrate workbench (22) for holding a substrate (21), wherein the substrate workbench (22) can be translated along the Y direction; A multi-nozzle system is located above the substrate workbench (22) and is movable along the Z-axis direction and the X-axis direction; the multi-nozzle system comprises a plurality of mutually independent non-metallic micro-nozzles (13) filled with a metal ion-nanoparticle mixture, and a micro-wire electrode (14) is inserted into the metal ion-nanoparticle mixture inside each of the non-metallic micro-nozzles (13); A micro-droplet dispensing device (19), wherein the cavity of each of the non-metallic micro-nozzles (13) is connected to the micro-droplet dispensing device (19); A voltage source (5) comprising a positive electrode and a negative electrode, wherein the positive electrode is electrically connected to the microwire electrode (14), and the negative electrode is electrically connected to the substrate (21), and is used to apply an electric field between the microwire electrode (14) and the substrate (21); A three-axis displacement system, connected to the substrate workbench (22) and the multi-nozzle system, respectively, for driving the substrate workbench (22) to move, and driving the multi-nozzle system to move; and a data acquisition system, the data acquisition system comprising an illumination device (20), a high-speed camera, a back pressure control system (9), a temperature controller (17) and a humidity controller (18); the high-speed camera is used to capture and analyze the flight state of the ionic droplets and the morphology of the micro-nanostructure in real time under the illumination of the illumination device (20); the back pressure control system (9) comprises a pneumatic regulating device (36), a control system (35), a gas pipeline (37) and a pressure sensor, and the gas is transmitted to the non-metallic micro nozzle (13) through the gas pipeline (37) to apply The back pressure controls the pressure of the solution in the non-metallic micro-nozzle (13); the pneumatic regulating device (36) is installed on the gas pipeline (37) for regulating the gas pressure; the pressure sensor is installed at the nozzle outlet of the non-metallic micro-nozzle (13) for real-time monitoring of the pressure at the nozzle outlet of the non-metallic micro-nozzle (13); the control system (35) is configured to adjust the pneumatic regulating device (36) according to the detection data of the pressure sensor; the temperature controller (17) and the humidity controller (18) are used to measure and control the printing temperature and humidity respectively; The metal ion-nanoparticle mixture in the non-metallic micro-nozzle (13) is ejected in the form of ion droplets encapsulating metal particles under the action of the electric field traction force and flies at high speed along the direction of the electric field lines to the surface to be deposited of the substrate (21). The substrate workbench (22) and the multi-nozzle system are driven to move relative to each other by the three-axis displacement system, and the electric field is controlled to achieve the preparation of the desired three-dimensional metal micro-nano structure on the surface to be deposited.

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