Method for realizing self-excitation maskless 3D printing by spraying liquid metal nanoparticles with aerosol

Abstract

The invention belongs to the field of aerosol 3D printing technology and liquid metal material processing, and particularly relates to a method for achieving maskless and self-excitation 3D printing through aerosol jet liquid metal nanoparticles. The liquid metal micro-nano particle ink is adopted for printing; the liquid metal micro-nano particle ink comprises a solvent, a surfactant and liquid metal micro-nano particles, the particle size of the liquid metal micro-nano particles is smaller than or equal to 5 micrometers, and oxidation films are arranged on the surfaces of the liquid metal micro-nano particles. In combination with an aerosol spraying 3D printing platform, liquid metal refined pattern, complex curved surface printing, mask-free, self-excitation and three-dimensional structure printing are achieved, the applicability and success rate of liquid metal printing are greatly improved, instability caused by high surface tension and fluidity of liquid metal is avoided, and the printing quality is improved. And a post-excitation step brought by nano-particle ink is omitted.

Description

Technical Field

[0001] The present invention belongs to the field of aerosol 3D printing technology / liquid metal material processing methods, and particularly relates to a method for aerosol jetting liquid metal nanoparticles to achieve self-excited and maskless 3D printing. Background Art

[0002] Aerosol 3D printing technology is a technology that uses a carrier gas, a focused gas flow, and a printing nozzle to jointly deposit an aerosol of (metal, ceramic, polymer, etc.) particles on the surface of a printing bed to achieve layer-by-layer stacking and construction of components. The general process of aerosol printing is as follows: Dispersing or dissolving the required material particles in a corresponding solvent to form a stable dispersion or solution, that is, preparing an "ink"; then atomizing the "ink" to generate a large number of micro-droplets, the micro-droplets enter the carrier gas to form an aerosol and are transported to the nozzle; finally, applying a surrounding gas at the nozzle to confine the aerosol into a beam with a diameter of 10 μm (micrometer) to 1 mm (millimeter), spraying it out at high speed and depositing it on the surface of the substrate, and forming a functional pattern under computer assistance.

[0003] However, the inherent fluidity of liquid metal brings instability, resulting in leakage and resistance change during the stretching process of the printed pattern, as well as problems such as difficulty in fine pattern / integration and open circuit under stretching due to its ultra-high surface tension.

[0004] To address these challenges, related technologies have proposed liquid metal nanoparticles with an oxide layer wrapped on the surface as a potential solution. This feature enhances mechanical and chemical stability, and improves compatibility with various solvents, fine pattern ability, and stable connection ability. In addition, a strong adhesion effect can be generated between the liquid metal and electronic components through the oxide layer, further improving the application ability of liquid metal in flexible circuits. Although nanoparticles have many advantages compared to traditional liquid metal inks, they are essentially insulating due to having an insulating oxide shell, so they cannot be directly used as electrodes. Therefore, it is necessary to make the nanoparticles conductive through a post-excitation process, resulting in multiple printing steps and complex operations. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for aerosol jetting liquid metal nanoparticles to achieve self-excited and maskless 3D printing. The printing method provided by the present invention realizes self-excitation of liquid metal, and no post-excitation treatment is required after printing, effectively simplifying the steps of liquid metal 3D printing and solving the problems of multiple steps and complex operations in aerosol 3D printing. At the same time, the method provided by the present invention realizes the printing of a three-dimensional structure with fine patterns on complex curved surfaces, greatly improving the applicability and success rate of liquid metal printing, and no hydrophilic treatment of the printing nozzle and substrate is required before printing.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for aerosol jetting liquid metal nanoparticles to achieve self-excited and maskless 3D printing, comprising the following steps:

[0008] Performing aerosol jetting 3D printing using liquid metal micro-nanoparticle ink;

[0009] The liquid metal micro-nanoparticle ink includes a solvent, a surfactant, and liquid metal micro-nanoparticles; the particle size of the liquid metal micro-nanoparticles ≤ 5 μm, the surface of the liquid metal micro-nanoparticles has an oxide film, and the mass ratio of the liquid metal micro-nanoparticles to the surfactant is (2 - 3.4):(0.01 - 0.1);

[0010] The flow rate of the conveying gas flow for the aerosol jetting 3D printing ≥ 0.1 slm.

[0011] Preferably, the dosage ratio of the liquid metal micro-nanoparticles to the solvent is (2 - 3.4) g:(10 - 15) mL.

[0012] Preferably, the liquid metal micro-nanoparticles are gallium-indium alloy micro-nanoparticles.

[0013] Preferably, the particle size of the liquid metal micro-nanoparticles is 0.1 - 5 μm.

[0014] Preferably, the flow rate of the conveying gas flow for the aerosol jetting 3D printing is 0.1 - 1.5 slm.

[0015] Preferably, the conditions for the aerosol jetting 3D printing further include: the flow rate of the focusing gas flow is 10 - 500 sccm; the diameter of the printing nozzle is 150 - 1000 μm; the printing height is 0.1 - 5 mm; the number of printing times is 1 - 18 times; the printing speed is 1 - 10 mm / s.

[0016] Preferably, the surfactant includes polyvinylpyrrolidone and / or n-octadecanethiol;

[0017] The average molecular weight of the polyvinylpyrrolidone is 40000 - 58000.

[0018] Preferably, the solvent includes one or more of acetone, dimethyl sulfoxide, alcohol solvents, and oil solvents.

[0019] Preferably, the preparation method of the liquid metal micro-nanoparticle ink includes the following steps:

[0020] Mixing the solvent, the surfactant, and the liquid metal to obtain a mixture;

[0021] Perform ultrasonic crushing treatment on the mixture to obtain the liquid metal micro-nano particle ink.

[0022] Preferably, the power of the ultrasonic crushing treatment is 150 - 450 W, the total time of the ultrasonic crushing treatment is 0.5 - 2.5 h, the time of a single ultrasonic crushing treatment is 3 - 5 s, and the interval time between two adjacent ultrasonic crushing treatments is 3 - 5 s.

[0023] The present invention provides a method for aerosol jet printing of liquid metal nanoparticles to achieve self-excitation and maskless 3D printing, which includes the following steps: performing aerosol jet 3D printing using the liquid metal micro-nano particle ink; the liquid metal micro-nano particle ink includes a solvent, a surfactant, and liquid metal micro-nano particles; the particle size of the liquid metal micro-nano particles ≤ 5 μm, the surface of the liquid metal micro-nano particles has an oxide film, and the mass ratio of the liquid metal micro-nano particles to the surfactant is (2 - 3.4):(0.01 - 0.1); the flow rate of the conveying air flow for the aerosol jet 3D printing ≥ 0.1 slm. The present invention uses the liquid metal micro-nano particle ink with an oxide film for aerosol jet 3D printing. By controlling the composition of the ink, the liquid metal with an oxide film on the surface in the ink exists in the form of micro-nano particles with a particle size ≤ 5 μm. At the same time, by controlling the flow rate of the conveying air flow for the aerosol jet 3D printing ≥ 0.1 slm, the liquid metal micro-nano particles can be made to have a high enough kinetic energy by the conveying air flow. When impacting the substrate, the kinetic energy of the liquid metal micro-nano particles is greater than the surface free energy of the liquid metal micro-nano particles (ΔKE = γΔA), and at the same time greater than the strain energy of the oxide skin on the surface of the liquid metal micro-nano particles ( unit N / m), to achieve fragmentation and polymerization to form a conductive path. The smaller unbroken particles (presenting a solid state due to being wrapped by a solid oxide film) are mixed with the polymerized liquid metal to form a solid-liquid two-phase liquid metal path (the solid phase therein is the small particles wrapped by the oxide film). The solid-liquid two-phase liquid metal path effectively enhances the stability of circuit stretching while ensuring good conductivity, realizes fine patterns of liquid metal, printing of complex curved surfaces, without a mask, self-excitation, and three-dimensional structure printing, greatly improves the applicability and success rate of liquid metal printing, and avoids the instability caused by the high surface tension and fluidity of liquid metal, as well as the damage problems of the substrate and the circuit that may be caused by the post-excitation treatment process. At the same time, the present invention optimizes the formula of the ink by reasonably controlling the dosage ratio of the surfactant and the liquid metal, reduces the surface tension of the liquid metal in the ink, and has a high printing success rate. Even when the flexible circuit is stretched and bent, the liquid metal in the ink is not easily broken due to polymerization, so that fine patterns of liquid metal can be realized; there is no need to perform a hydrophilic treatment on the substrate and the printing nozzle in advance, shortening the process.

[0024] In summary, the aerosol jet printing method for self-excited and maskless 3D printing of liquid metal nanoparticles provided by the present invention uses an aerosol jet printing method, which does not need to be in direct contact with the bottom surface and does not require a mask, realizing the processing of complex curved surfaces of liquid metals. At the same time, the ink provided by the present invention can realize a solid-liquid biphasic liquid metal circuit, improving the electrical stability of the circuit in the stretched state.

[0025] Further, in the present invention, the particle size of the liquid metal micro-nanoparticles is 0.1 - 5 μm, and the flow rate of the conveying gas for aerosol jet 3D printing is 0.1 - 1.5 slm. By regulating the particle size and the conveying flow rate, the present invention can further optimize the atomization rate and deposition rate of the ink, and further optimize the fragmentation ratio of the liquid metal micro-nanoparticles in the ink, thereby improving the conductivity and printing accuracy of the printing. Thus, the 3D printing effect of fine patterns on complex surfaces is optimized, and maskless and self-excited printing are successfully achieved, and the steps are simple and easy to implement.

[0026] Further, in the present invention, the flow rate of the focusing gas is 10 - 500 sccm. The present invention further improves the printing accuracy by controlling the flow rate of the focusing gas.

[0027] Further, the present invention provides a method for preparing the liquid metal micro-nanoparticle ink, including the following steps: mixing a solvent, a surfactant, and liquid metal to obtain a mixture; performing ultrasonic fragmentation treatment on the mixture to obtain the liquid metal micro-nanoparticle ink. By mixing a solvent, a surfactant, and liquid metal and then performing ultrasonic fragmentation treatment, the present invention can obtain a liquid metal ink in the form of micro-nanoparticles, and the liquid metal micro-nanoparticle ink has good mechanical and chemical stability. Description of the Drawings

[0028] Figure 1 It is an electron microscope photograph of the liquid metal micro-nanoparticle ink prepared in Example 1 of the present invention;

[0029] Figure 2 It is a cross-sectional solid-liquid biphasic SEM characterization diagram of the printing in Example 2 of the present invention;

[0030] Figure 3 It is the printing result on the leaf surface in Example 2 of the present invention;

[0031] Figure 4 It is a printing line width SEM characterization diagram of Example 2 of the present invention;

[0032] Figure 5 It is a printing resistance test diagram of Example 2 of the present invention;

[0033] Figure 6 It is a relationship diagram between the printing conductivity and various substrates in Example 2 of the present invention.

[0034] Figure 7 This is the overall structure diagram of the device used in the method for maskless 3D printing by aerosol jetting of liquid metal nanoparticles provided by the present invention. Detailed implementation mode

[0035] The present invention provides a method for self-excited and maskless 3D printing by aerosol jetting of liquid metal nanoparticles, comprising the following steps:

[0036] Performing aerosol jetting 3D printing using a liquid metal micro-nanoparticle ink;

[0037] The liquid metal micro-nanoparticle ink comprises a solvent, a surfactant, and liquid metal micro-nanoparticles; the particle size of the liquid metal micro-nanoparticles ≤ 5 μm, the surface of the liquid metal micro-nanoparticles has an oxide film, and the mass ratio of the liquid metal micro-nanoparticles to the surfactant is (2 - 3.4):(0.01 - 0.1);

[0038] The flow rate of the conveying gas flow for the aerosol jetting 3D printing ≥ 0.1 slm.

[0039] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well-known to those skilled in the art.

[0040] The present invention performs aerosol jetting 3D printing using a liquid metal micro-nanoparticle ink.

[0041] The liquid metal micro-nanoparticle ink provided by the present invention comprises a solvent. In the present invention, the solvent preferably comprises one or more of acetone, dimethyl sulfoxide (DMSO), alcohol solvents, and oil solvents. The alcohol solvents preferably comprise one or more of ethanol, isopropanol, and butanol. The oil solvent preferably comprises hexadecane. In a specific embodiment of the present invention, the solvent is specifically ethanol.

[0042] The liquid metal micro-nanoparticle ink provided by the present invention comprises a surfactant. In the present invention, the surfactant preferably comprises polyvinylpyrrolidone and / or n-octadecanethiol, and is specifically polyvinylpyrrolidone (PVP) in the examples. In the present invention, the average molecular weight of the polyvinylpyrrolidone is preferably 40000 - 58000, and can be 58000 in the examples. The polyvinylpyrrolidone is preferably k29 - 32. The present invention preferably uses PVP as the surfactant in the liquid metal micro-nanoparticle ink, and simultaneously controls the mass ratio of the liquid metal micro-nanoparticles to the surfactant. When the dosage of PVP is too large, the viscosity of the ink increases, the atomization rate decreases, the deposition rate of the liquid metal in the ink decreases, resulting in poor conductivity and an increase in resistance. In addition, when the dosage of PVP is too large, since PVP is not conductive and is not easily volatile, it affects the conductivity of the electrode.

[0043] The liquid metal micro-nano particle ink provided by the present invention comprises liquid metal micro-nano particles, and an oxide film is present on the surface of the liquid metal micro-nano particles. In the present invention, the liquid metal micro-nano particles are preferably gallium-indium alloy micro-nano particles. The gallium-indium alloy is specifically Ga75In25. The particle size of the liquid metal micro-nano particles is ≤5 μm, preferably 0.1 - 5 μm, and more preferably 0.1 - 4 μm.

[0044] In the present invention, the mass ratio of the liquid metal micro-nano particles to the surfactant is (2 - 3.4):(0.01 - 0.1), preferably (2.5 - 3):(0.01 - 0.05), and more preferably (2.5 - 3):0.01. Specifically, in the examples, it is 2.64:0.01.

[0045] In the present invention, the dosage ratio of the liquid metal micro-nano particles to the solvent is preferably (2 - 3.4) g:(10 - 15) mL, more preferably (2.5 - 3) g:(10 - 12) mL, and further preferably (2.5 - 3) g:10 mL. Specifically, in the examples, it is 2.64 g:10 mL.

[0046] In the present invention, when the dosage of the liquid metal in the liquid metal micro-nano particle ink is too large, the viscosity of the ink becomes larger, the atomization rate of the liquid metal ink is reduced, the deposition rate decreases, and the conductivity is affected. In addition, under the condition that the ultrasonic parameters remain unchanged, the liquid metal with too high a content cannot be completely broken, resulting in an increase in particle size, and the larger particle size cannot be atomized, which also limits the further improvement of the deposition rate and conductivity.

[0047] In the present invention, the liquid metal in the liquid metal micro-nano particle ink is nano-particles wrapped by an oxide film. Since liquid metal has extremely strong reducibility, it will be rapidly oxidized when exposed to air. During the ultrasonic fragmentation process of the present invention, the oxide film wraps the liquid metal and disperses the massive liquid metal into micro-nano particles.

[0048] The present invention combines the liquid metal micro-nano particle ink with the high flow rate generated by aerosol jetting. Under the action of kinetic energy, the liquid metal micro-nano particles impinging on the substrate are broken and polymerized to form a conductive path, while the smaller unbroken liquid metal micro-nano particles (preferably less than 300 nm) are mixed with the polymerized liquid metal to form a solid-liquid two-phase liquid metal path, which enhances the stability of circuit stretching while ensuring good conductivity.

[0049] The aerosol jet 3D printing method provided by the present invention uses an ink containing liquid metal micro-nano particles in a dispersed state during the printing process. During the printing process, due to the high flow rate of the aerosol jet (the flow rate of the conveying gas ≥ 0.1 slm), the liquid metal micro-nano particles can be made to impact and aggregate. By controlling the flow rate of the conveying gas, the size and proportion of the broken particles of the liquid metal micro-nano particles are adjusted to achieve a controllable solid-liquid biphasic ink.

[0050] The present invention provides a method for preparing the liquid metal micro-nano particle ink described in the above technical solution, comprising the following steps:

[0051] Mix a solvent, a surfactant, and liquid metal to obtain a mixture;

[0052] Perform ultrasonic fragmentation treatment on the mixture to obtain the liquid metal micro-nano particle ink.

[0053] The present invention mixes a solvent, a surfactant, and liquid metal to obtain a mixture. The present invention has no special requirements for the specific operation of the mixing.

[0054] After obtaining the mixture, the present invention performs ultrasonic fragmentation treatment on the mixture to obtain the liquid metal micro-nano particle ink. In the present invention, the ultrasonic fragmentation treatment is preferably carried out using an ultrasonic fragmentation instrument. The diameter of the ultrasonic probe used in the ultrasonic fragmentation treatment is preferably 2 - 8 mm. The power of the ultrasonic fragmentation treatment is preferably 150 - 450 W, more preferably 200 - 450 W, and specifically 400 W in the examples. The total time of the ultrasonic fragmentation treatment is preferably 0.5 - 2.5 h, more preferably 1 - 2.5 h, and specifically 2.5 h in the examples. The time of a single ultrasonic fragmentation treatment is preferably 3 - 5 s, more preferably 4 - 5 s, and specifically 5 s in the examples. The interval time between two adjacent ultrasonic fragmentation treatments is preferably 3 - 5 s, more preferably 4 - 5 s, and specifically 5 s in the examples.

[0055] In the present invention, the aerosol jet 3D printing method is preferably carried out using an aerosol printing system. The aerosol printing system preferably includes a first flow controller, a second flow controller, a three-axis desktop robot (i.e., a dispensing machine), an aerosol printing nozzle, and an atomizer.

[0056] In the present invention, the specific implementation method of the aerosol jet 3D printing method preferably includes: connecting the first nitrogen gas path as the conveying gas flow to the atomizer through the first flow controller, and connecting the atomizer to the conveying gas flow port of the aerosol printing nozzle. The second nitrogen gas path is used as the focusing gas flow and is connected to the focusing gas flow port of the aerosol printing nozzle through the second flow controller. Both the first flow controller and the second flow controller are connected to a computer to achieve digital control. Adding the liquid metal micro-nano particle ink described in the above technical solution into the atomizer, adjusting the atomization rate, deposition rate, printing speed, fragmentation state, conductivity and printing accuracy of the ink by adjusting the flow rate of the conveying gas flow at the computer end. Further improving the printing accuracy by adjusting the flow rate of the focusing gas flow. Installing the aerosol printing nozzle on a three-axis desktop robot, connecting the computer to the three-axis desktop robot, and programming the printing path and the moving speed of the aerosol printing nozzle to achieve 3D printing using the liquid metal micro-nano particle ink described in the above technical solution.

[0057] The present invention has no special requirements for the substrate material used in the aerosol jet 3D printing. In the embodiments, it can be an organic substrate, a silicon wafer (Si Wafer) substrate, a SiO2 substrate or a plant leaf; the organic substrate includes an ecoflex substrate, a polydimethylsiloxane (PDMS) substrate or a polyimide (PI) substrate.

[0058] In the present invention, the printing conditions preferably include: the flow rate of the conveying gas is preferably 0.1 - 1.5 slm, more preferably 0.1 - 0.5 slm, and specifically 0.5 slm in the examples. In the present invention, if the flow rate of the conveying gas is too large or too small, it will affect the conductivity (electric conductivity) of the printing. The flow rate of the focusing gas is preferably 10 - 500 sccm, and specifically 500 sccm in the examples. In the present invention, if the flow rate of the focusing gas is too small, the printing accuracy will deteriorate, and if it is too large, the deposition rate of the liquid metal will decrease. In the present invention, the diameter of the printing nozzle is preferably 150 - 1000 μm, and specifically 400 μm in the examples. The printing height is preferably 0.1 - 5 mm, more preferably 0.1 - 1 mm, and specifically 0.5 mm in the examples. The printing height is the vertical height of the printing nozzle from the substrate. The number of printing times is preferably 1 - 18 times, more preferably 1 - 12 times, and specifically 9 times in the examples. The printing speed is preferably 1 - 10 mm / s, more preferably 1 - 5 mm / s, and specifically 3 mm / s in the examples. In a specific embodiment of the present invention, one of the printing paths is specifically a straight line of 10 mm. The aerosol jet 3D printing method provided by the present invention uses the liquid metal micro-nano particle ink described in the above technical solution, and uses the conveying gas to make the liquid metal micro-nano particles have sufficient high kinetic energy. When impacting the substrate, the kinetic energy is greater than the surface free energy of the liquid metal and at the same time greater than the strain energy of the oxide skin on the surface of the liquid metal particles, realizing fragmentation polymerization and conductivity, successfully realizing maskless, self-excited, fine pattern, complex curved surface, and three-dimensional structure printing.

[0059] The present invention provides a method for aerosol jet printing of liquid metal nanoparticles to achieve self-excited and maskless 3D printing. The present invention ingeniously combines the liquid metal micro-nano particle ink wrapped by an oxide film with the high flow rate generated by aerosol jet. Under the action of kinetic energy, the nano-particles impacting the substrate achieve fragmentation polymerization to form a conductive path. The smaller particles (less than 300 nm) that are not fragmented are mixed with the polymerized liquid metal to form a solid-liquid two-phase liquid metal path, which not only ensures good conductivity but also enhances the stability of the circuit stretching. Combining with the aerosol jet 3D printing platform, the advantages of fine patterns of liquid metal, complex curved surface printing, maskless, self-excitation and three-dimensional structure printing are realized; moreover, there is no need to perform a hydrophilic treatment on the printing nozzle and the substrate before printing. There is no need for post-excitation treatment after printing, which greatly improves the applicability and success rate of liquid metal printing, avoids the instability caused by the high surface tension and fluidity of liquid metal, solves the post-excitation step brought by the nano-particle ink, and effectively simplifies the steps of liquid metal 3D printing.

[0060] In order to further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below in conjunction with the examples, but they cannot be understood as limiting the protection scope of the present invention.

[0061] Example 1

[0062] This example provides a method for preparing a liquid metal micro-nano particle ink, which is as follows:

[0063] Mix 10 mL of absolute ethanol (purchased from Beijing Lanyi Chemical Products Co., Ltd.), 2.67 g of gallium-indium alloy (Ga75In25, purchased from Dongguan Qiaotai Metal Technology Co., Ltd.), and 0.01 g of PVP (Shanghai Macklin Biochemical Co., Ltd.) to obtain a mixed material.

[0064] Use an ultrasonic crushing instrument to perform ultrasonic crushing treatment on the mixed material, and crush the liquid metal in the mixed material into particles with a particle size of 0.5 - 1.0 microns. During the ultrasonic crushing treatment, the diameter of the ultrasonic probe is 6 mm, the ultrasonic power is 400 W, the total ultrasonic time is 2.5 h, the single ultrasonic time is 5 s, and the interval time is 5 s to obtain a liquid metal micro-nano particle ink.

[0065] Figure 1 This is the electron microscope photograph of the liquid metal micro-nano particle ink prepared in Example 1 of the present invention. As can be seen from Figure 1 it, in the liquid metal micro-nano particle ink prepared in Example 1, the gallium-indium alloy exists in the form of micro-nano particles, and the particle size of the gallium-indium alloy micro-nano particles < 4 μm.

[0066] Example 2

[0067] This example provides a method for aerosol jetting liquid metal nanoparticles to achieve self-excited and maskless 3D printing, Figure 7 which is the overall structure diagram of the equipment used for the method of aerosol jetting liquid metal nanoparticles to achieve maskless 3D printing in this example; specifically includes the following steps:

[0068] The aerosol printing system used in this example includes: 2 flow controllers, a three-axis desktop robot (dispensing machine), an aerosol printing nozzle, and an atomizer.

[0069] The substrate materials for aerosol jetting 3D printing in this example are: EcoFlex, PDMS, PI, SiWafer, SiO2 glass, or a leaf.

[0070] First, connect the nitrogen gas path to the input end of the atomizer through a flow controller as the conveying gas flow, and connect the output end to the inlet of the printing nozzle. The three-axis desktop robot (i.e., the dispensing machine) is connected to the computer, import the planned printing path into the dispensing program, and add the liquid metal micro-nano particle ink prepared in Example 1 into the atomizer.

[0071] Specifically: The first nitrogen gas path is connected to the input end of the atomizer through the first flow controller as the conveying air flow, and the atomizer is connected to the conveying air flow port of the aerosol printing nozzle. The second nitrogen gas path is connected to the focusing air flow port of the aerosol printing nozzle through the second flow controller. Both the first flow controller and the second flow controller are connected to the computer to achieve digital control. The liquid metal micro-nano particle ink prepared in Example 1 is added to the atomizer, and the atomization rate, deposition rate, ink jet printing speed, fragmentation state, conductivity, and printing accuracy of the ink are adjusted by adjusting the flow rate of the conveying air flow at the computer terminal. The printing accuracy is further improved by adjusting the flow rate of the focusing air flow. The aerosol printing nozzle is installed on a three-axis desktop robot, connected to the three-axis desktop robot through the computer, and the printing path and the moving speed of the aerosol printing nozzle are programmed to achieve 3D printing of the liquid metal micro-nano particle ink prepared in Example 1. Among them, the conditions for 3D printing include: the flow rate of the conveying air flow is 0.5 slm; the flow rate of the focusing air flow is 500 sccm; the diameter of the printing nozzle is 400 microns; the printing height (0.5 mm from the substrate); the number of printing times is 9 times; the printing speed is 3 mm / s; one of the printing paths is: a straight line of 10 mm.

[0072] Figure 2 This is the cross-sectional SEM characterization diagram of the solid-liquid biphasic liquid metal path formed during printing on a silicon wafer (Si Wafer) substrate in Example 2 of the present invention. It is shown by Figure 2 that self-excited fragmentation and the liquid metal biphasic path can be proven, and the maximum particle size of the unbroken particles is about 357 nm.

[0073] Figure 3 This is the pattern printed on the Epipremnum aureum leaf surface in Example 2 of the present invention. It can be seen from Figure 3 that the method for aerosol jet 3D printing using the liquid metal micro-nano particle ink prepared in Example 1 provided by the present invention can achieve fine-pattern printing of liquid metal on the surface of complex substrates, with a printing line width of 100 μm.

[0074] Figure 4 This is the SEM characterization diagram of the printing line width on the SiO2 glass substrate surface in Example 2 of the present invention; it can be seen from Figure 4 that the method for aerosol jet 3D printing using the liquid metal micro-nano particle ink prepared in Example 1 provided by the present invention has a high printing temperature rise accuracy, and the printing line width accuracy is about 50 μm. Through experimental research, it is proven that the method for aerosol jet printing of liquid metal nanoparticles provided by the present invention to achieve maskless and self-excited 3D printing has a high printing accuracy, and the minimum printing line width accuracy can reach 40 μm.

[0075] Figure 5 This is the resistance test diagram of the printing on the SiO2 glass substrate surface in Example 2 of the present invention; it is shown by Figure 5It can be seen that the method of aerosol jet 3D printing using the liquid metal micro-nano particle ink prepared in Example 1 of the present invention has a resistance of 0.8 ohms (multimeter).

[0076] Figure 6 This is the relationship diagram between the printing conductivity and various substrates in Example 2 of the present invention. From Figure 6 It can be seen that the method of aerosol jet 3D printing using the liquid metal micro-nano particle ink prepared in Example 1 of the present invention can achieve the effect of high printing conductivity on different substrate materials, and the highest conductivity is 2.1×10 6 S / m.

[0077] From the above examples, it can be seen that the present invention provides a liquid metal micro-nano particle ink, in which the liquid metal is in the form of micro-nano particles, thereby enhancing the mechanical and chemical stability of the liquid metal in the ink and improving the compatibility of the ink with various processes, and can be printed by extrusion printing.

[0078] The present invention provides a method of aerosol jet 3D printing using liquid metal micro-nano particle ink. By using the conveying air flow, the liquid metal micro-nano particles in the ink have sufficient high kinetic energy. When impacting the substrate, the kinetic energy is greater than the surface free energy of the liquid metal, and greater than the strain energy of the oxide skin on the surface of the liquid metal particles, realizing fragmentation and polymerization conductivity, and successfully realizing maskless, self-excited, fine pattern, complex curved surface, and three-dimensional structure printing.

[0079] In summary, the printing method provided by the present invention solves the problems of inability to perform fine patterning due to the high surface tension when using liquid metal ink for printing, and the need for hydrophilic treatment of the printing nozzle and substrate before printing. It also solves the instability caused by the fluidity of the liquid metal, and at the same time solves the post-treatment process that requires excitation after printing the liquid metal ink and the possible damage to the substrate and circuit caused by this process. The printing method provided by the present invention realizes the advantages of fine patterning of liquid metal, complex curved surface printing, maskless, self-excitation and three-dimensional structure printing. At the same time, conductivity regulation can be achieved. From the results of the examples, it can be seen that the aerosol jet 3D printing method provided by the present invention realizes the highest conductivity of 2.1×10 6 S / m, the minimum printing accuracy is 40μm, and conductivity regulation can be achieved at the same time.

[0080] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all embodiments. Other embodiments can be obtained according to these embodiments without creative efforts, and these embodiments all belong to the protection scope of the present invention.

Claims

1. A method for realizing self-excited and maskless 3D printing by aerosol jetting liquid metal nanoparticles, characterized in that, Including the following steps: Using liquid metal micro-nano particle ink for aerosol jet 3D printing; The liquid metal micro-nano particle ink includes a solvent, a surfactant, and liquid metal micro-nano particles; the particle size of the liquid metal micro-nano particles ≤ 5 μm, the surface of the liquid metal micro-nano particles has an oxide film, and the mass ratio of the liquid metal micro-nano particles to the surfactant is (2 - 3.4):(0.01 - 0.1); The flow rate of the conveying air flow for the aerosol jet 3D printing ≥ 0.1 slm.

2. The aerosol jetting liquid metal nanoparticle-based self-excited and maskless 3D printing method according to claim 1, wherein The dosage ratio of the liquid metal micro-nano particles to the solvent is (2 - 3.4) g:(10 - 15) mL.

3. The aerosol jetting liquid metal nanoparticle self-excited and maskless 3D printing method according to claim 1, wherein The liquid metal micro-nano particles are gallium-indium alloy micro-nano particles.

4. The aerosol jetting liquid metal nanoparticle self-excited and maskless 3D printing method according to claim 1 or 3, characterized in that, The particle size of the liquid metal micro-nano particles is 0.1 - 5 μm.

5. The aerosol jetting liquid metal nanoparticle self-excited and maskless 3D printing method according to claim 1, characterized in that, The flow rate of the conveying air flow for the aerosol jet 3D printing is 0.1 - 1.5 slm.

6. The aerosol jetting liquid metal nanoparticle-based self-excited and maskless 3D printing method according to claim 1 or 5, wherein The conditions for the aerosol jet 3D printing further include: the flow rate of the focusing air flow is 10 - 500 sccm; the diameter of the printing nozzle is 150 - 1000 μm; the printing height is 0.1 - 5 mm; the number of printing times is 1 - 18 times; the printing speed is 1 - 10 mm / s.

7. The aerosol jetting liquid metal nanoparticle-based self-excited and maskless 3D printing method according to claim 1, wherein The surfactant includes polyvinylpyrrolidone and / or n-octadecanethiol; The average molecular weight of the polyvinylpyrrolidone is 40000 - 58000.

8. The aerosol jet liquid metal nanoparticle-based self-excited and maskless 3D printing method according to claim 1, characterized in that The solvent includes one or more of acetone, dimethyl sulfoxide, alcohol solvents, and oil solvents.

9. The aerosol jetting liquid metal nanoparticle self-excitation and maskless 3D printing method according to claim 1, characterized in that, The preparation method of the liquid metal micro-nano particle ink includes the following steps: Mixing the solvent, the surfactant, and the liquid metal to obtain a mixture; Performing ultrasonic fragmentation treatment on the mixture to obtain the liquid metal micro-nano particle ink.

10. The aerosol jetting liquid metal nanoparticle self-excited and maskless 3D printing method according to claim 9, wherein, The power of the ultrasonic fragmentation treatment is 150 - 450 W, the total time of the ultrasonic fragmentation treatment is 0.5 - 2.5 h, the time of a single ultrasonic fragmentation treatment is 3 - 5 s, and the interval time between two adjacent ultrasonic fragmentation treatments is 3 - 5 s.

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