Method for regulating and controlling three-dimensional structure of pen type direct writing 3D printing micro-nano device based on shapes of nano-particles

Abstract

The invention relates to a method for regulating and controlling a three-dimensional structure of a pen-type direct-writing 3D printing micro-nano device based on shapes of nanoparticles. The method comprises the following steps: S1, determining a 3D printing sequence, slicing information and a substrate heating temperature of a to-be-printed device; s2, a precursor mixed solution for 3D printing of the to-be-printed device is placed in a capillary tube, the height is adjusted, so that an initial meniscus appears between an outlet of the capillary tube and a substrate, and the precursor mixed solution is a solution containing spherical nano-particles or non-spherical nano-particles; and S3, based on the 3D printing sequence and the slicing information determined in the step S1 and the initial meniscus in the step S2, the environment humidity and the environment temperature are adjusted, and the 3D printing process is movably executed. Compared with the prior art, through the morphological change of the nanoparticles, the diversity and complexity of the printing structure are enhanced, and meanwhile dependence on complex auxiliary equipment or limitation of material selection is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and in particular to a method for regulating the three-dimensional structure of a micro-nano device by pen-type direct writing 3D printing based on the shape of nanoparticles. Background Art

[0002] In the field of micro-nanoscale 3D printing technology, precise control of the printed three-dimensional structures, such as micropillars and microtubes, is critical to the manufacture of high-performance micro-nano devices. Micropillar arrays and microtubular arrays have shown significant application value in many fields such as optics, electronics, and biomedicine due to their unique geometric characteristics. Such structures play a decisive role in improving the performance of optical devices, enhancing the performance of electronic devices, and promoting biomedical research. However, the manufacturing process of these fine structures still faces many challenges such as precision control and material compatibility, which limits their application potential in a wider range of fields.

[0003] The main methods to print microcolumns and microtubes at the micro-nano scale include micro stereolithography (MSLA), micro laser sintering (MSLS), fused deposition modeling (FDM), template-assisted assembly (TAA) and electrochemical etching method (ECM).

[0004] Among them, micro-stereolithography technology uses controllable light to irradiate photosensitive resin to solidify the entire layer and obtain a three-dimensional structure. However, printing columnar or tubular structures with a large aspect ratio is limited by factors such as the resin's own gravity and curing shrinkage, which can easily cause the columnar or tubular structure to deform, bend or even collapse. For example, gravity breaks the stress distribution or curing shrinkage causes internal stress accumulation that exceeds the material's tolerance limit.

[0005] Micro laser sintering technology builds objects by sintering layer by layer, and its surface roughness is often high. For structures with a large aspect ratio, this surface roughness problem may be more prominent, and additional processing is often required to improve the surface quality, which increases the process flow and cost.

[0006] Fused deposition modeling is an additive manufacturing technology that builds objects by heating filamentary materials to a molten state and then extruding them through capillaries to accumulate and solidify layer by layer. However, due to the relatively weak bonding strength between layers, when printing structures with a large aspect ratio, delamination is prone to occur, reducing the overall strength and stability of the structure.

[0007] Template interface assisted assembly uses capillary force to guide the reaction solution into the porous template, and realizes the precise construction of soft conductive polymer nanorod / tube arrays through interfacial polymerization. This method is limited by the need for additional steps to remove the template or perform subsequent surface treatment, which increases the complexity and cost of the manufacturing process.

[0008] The dye etching method uses the oxidation reaction induced by oxidants in fluorine-containing solutions, as well as the formation and regulation of the space charge layer (SCR), to achieve the transformation of silicon micropillar arrays into porous silicon microtube structures. However, this method is limited by the fact that micropillars must be formed before microtubes can be achieved, and it is mainly applicable to silicon materials, requiring complex steps and a variety of etching solution configurations.

[0009] In comparison, direct writing technology has become an ideal choice for 3D printing of micro-nano structures due to its advantages such as easy control of micro-nano structures, low cost, rapid prototyping, easy operation of printing equipment, and environmentally friendly printing process. However, there is no clear conclusion on how to controllably print micro-columns or micro-tubes based on this method. Summary of the invention

[0010] The purpose of the present invention is to clarify how to controllably print microcolumns or microtube structures in a pen-type direct writing 3D printing method, thereby providing a method for regulating the three-dimensional structure of pen-type direct writing 3D printed micro-nano devices based on the shape of nanoparticles.

[0011] The purpose of the present invention can be achieved by the following technical solutions:

[0012] One of the technical solutions of the present invention is to provide a method for controlling the three-dimensional structure of a micro-nano device by pen-type direct writing 3D printing based on the shape of nanoparticles, comprising the following steps:

[0013] S1. Determine the 3D printing sequence, slicing information, and substrate heating temperature of the device to be printed;

[0014] S2, placing the precursor mixture for 3D printing the device to be printed in the capillary, and adjusting the height so that an initial curved liquid surface appears between the outlet of the capillary and the substrate,

[0015] Wherein, the precursor mixture is a solution containing spherical nanoparticles or non-spherical nanoparticles;

[0016] S3, based on the 3D printing sequence and slicing information determined in step S1, and the initial curved liquid surface in step S2, the ambient humidity and ambient temperature are adjusted, and the 3D printing process is performed by moving.

[0017] In some specific embodiments, in step S2, the precursor mixture is a solution of any one or more selected from aluminum oxide nanoparticles, titanium dioxide nanoparticles, graphene oxide nanoparticles, molybdenum trioxide nanoparticles, and PMMA / PPy composite nanoparticles.

[0018] In some specific embodiments, the aluminum oxide nanoparticles and titanium dioxide nanoparticles are spherical in shape, and the graphene oxide nanoparticles, molybdenum trioxide nanoparticles and PMMA / PPy composite nanoparticles are non-spherical in shape.

[0019] In some specific embodiments, when the precursor mixed solution is an aluminum oxide nanoparticle solution, the aluminum oxide nanoparticles are spherical in shape, with a particle size of 10 to 20 nm, and a mass fraction of the solution is 15 to 25 wt %.

[0020] In some specific embodiments, when the precursor mixed solution is a titanium dioxide nanoparticle solution, the titanium dioxide nanoparticles are spherical in shape, with a particle size of 10 to 20 nm, and a mass fraction of the solution is 25 to 30 wt %.

[0021] In some specific embodiments, when the precursor mixture is a graphene oxide nanoparticle solution, the graphene oxide nanoparticles are in the shape of flakes, with a flake diameter of 0.1 to 10 μm and a thickness of 0.6 to 1 nm, and the concentration of the solution is 2-10 mg / mL.

[0022] In some specific embodiments, when the precursor mixture is a molybdenum trioxide nanoparticle solution, the molybdenum trioxide nanoparticles are rod-shaped with a diameter of 10 to 20 nm and a length of 100 to 150 nm, and the mass fraction of the solution is 0.5 to 20 wt%.

[0023] In some specific embodiments, when the precursor mixture is a PMMA / PPy composite nanoparticle solution, the PMMA / PPy composite nanoparticles are fibrous in shape with a diameter of 30-40 nm, the mass ratio of PMMA to PPy is 1:2.5, and the mass fraction of the solution is 15-20 wt%.

[0024] In some specific embodiments, in step S2, the height of the initial curved liquid surface between the outlet of the capillary and the substrate ranges from 25 to 55 μm, and the longitudinal cross-section of the initial curved liquid surface is an arc-shaped curve profile with large dimensions at the upper and lower ends and a small dimension in the middle part, and the overall structure is cylindrical.

[0025] In some specific embodiments, when the nanoparticles in the precursor mixture are spherical in shape, the height of the initial meniscus between the capillary outlet and the substrate is in the range of 30 μm±5 μm, and the maximum diameter of the initial meniscus is smaller than the inner diameter of the capillary.

[0026] In some specific embodiments, when the nanoparticles in the precursor mixture are non-spherical in shape, the height of the initial meniscus between the capillary outlet and the substrate is in the range of 50 μm±5 μm, and the maximum diameter of the initial meniscus is smaller than the outer diameter of the capillary.

[0027] In some specific embodiments, in step S2, the contact angle between the substrate and the precursor mixture is 80°. When the contact angle between the precursor mixture and the substrate material is small, the printed solution is easily spread over a large area on the substrate, which may make it impossible to achieve accurate bottom-up printing; when the contact angle is too large, the contact between the precursor mixture and the substrate becomes difficult, and it is difficult to use surface tension to make the precursor mixture flow out continuously, affecting the printing effect.

[0028] In some specific embodiments, in step S3, the ambient humidity is 50% to 60%, and the ambient temperature is room temperature.

[0029] In some specific embodiments, in step S3, the 3D printing process also includes: starting printing from the bottom layer of the printing order, moving at a set speed and path, and the precursor mixture continues to flow out and deposit under the traction of the curved liquid surface until the printing is completed to form the required structure.

[0030] The second technical solution of the present invention is to provide a 3D printed microcolumn, based on the method described in one of the above technical solutions, wherein the precursor mixed solution is selected from any one or more of a spherical aluminum oxide nanoparticle solution and a spherical titanium dioxide nanoparticle solution.

[0031] The third technical solution of the present invention is to provide a 3D printed microtube, based on the method described in one of the above technical solutions, wherein the precursor mixed liquid is selected from any one or more of a flaky graphene oxide nanoparticle solution, a rod-shaped molybdenum trioxide nanoparticle solution, and a fibrous PMMA / PPy composite material nanoparticle solution.

[0032] The present invention achieves precise control of the printed structure morphology by finely regulating the shape of nanoparticles in the precursor mixture and utilizing the difference in their adsorption force on the gas-liquid interface. This control is achieved by deeply understanding the behavior of nanoparticles on the surface of the meniscus and their interaction with the evaporation dynamics of the solvent.

[0033] Spherical nanoparticles have a weaker adsorption force on the gas-liquid interface due to their surface geometric characteristics. In the dynamic process of micro-nano 3D printing, as the solvent continues to evaporate, the adsorption force of spherical nanoparticles on the gas-liquid interface is relatively weak. Under this condition, random diffusion transport of particles becomes the dominant mechanism. Figure 2As shown in Figures A, 3 and 4, due to the concentration gradient caused by solvent evaporation, the spherical particles undergo non-directional Brownian motion on the surface of the droplet, thereby achieving uniform deposition on the substrate and finally forming a microcolumn structure.

[0034] In contrast, non-spherical nanoparticles exhibit stronger adsorption to the air-liquid interface due to their larger adsorption energy. Figure 2 As shown in Figures B, 5, and 6, during the printing process, non-spherical particles are more likely to be arranged horizontally at the gas-liquid interface to form a particle layer. As the solvent continues to evaporate, the arrangement of these non-spherical particles at the interface gradually solidifies to form a stable microtubule structure. The formation of this structure is due to the mutual connection and bridging effect of the non-spherical particles at the interface. They form a tubular structure with certain mechanical strength through van der Waals forces or other intermolecular forces.

[0035] By precisely adjusting the shape and size of nanoparticles, the present invention can achieve precise control of the printed structure morphology, thereby printing a variety of micro-nano device three-dimensional structures. By changing the aspect ratio of non-spherical particles, the wall thickness and diameter of the microtube can be controlled to meet the needs of different application scenarios.

[0036] The formula for the adsorption energy is as follows

[0037]

[0038] in:

[0039] E ad is the adsorption energy of the particle at the liquid-gas interface.

[0040] γ is the surface tension of water.

[0041] h is the distance from the particle center of mass to the liquid-air interface.

[0042] a is the semi-minor axis of the particle.

[0043] θ is the water contact angle on the particle surface.

[0044] G(k) is the geometric correction factor of the ellipsoid, and k is the aspect ratio of the ellipsoid.

[0045]

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) Ability to regulate the shape of nanoparticles: The present invention achieves precise control of the morphology of printed structures by precisely controlling the shape of nanoparticles in the precursor mixture, such as spherical or non-spherical, thereby printing micro-nano devices of different shapes such as microcolumns or microtubes.

[0048] (2) Direct printing of three-dimensional structures: By controlling the adsorption characteristics and deposition process of the gas-liquid interface, the present invention can directly print complex three-dimensional structures without the need for subsequent assembly or processing steps.

[0049] (3) Dual improvement in printing accuracy and efficiency: The present invention can not only achieve micron or even nanometer-level printing accuracy, but also significantly improve manufacturing efficiency by simplifying the printing process.

[0050] (4) Environmental friendliness and cost-effectiveness: It reduces dependence on molds and support structures, reduces material waste and manufacturing costs, and reduces the impact on the environment. The molding scale reaches the micro-nano level and is highly scalable. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a schematic diagram of the structure of a pen-type direct writing 3D printing device.

[0052] Figure 2 A is a schematic diagram of the principle of pen-type direct writing 3D printing based on spherical alumina; Figure 2 B is a schematic diagram of the principle of pen-type direct writing 3D printing based on flake graphene oxide.

[0053] Figure 3 This is a complete microcolumn printing process in an embodiment of the present invention, wherein the printing speed is 1.75 μm / s, the capillary diameter is 75 μm, the precursor mixture is an aluminum oxide dispersion, and the nanoparticle shape is spherical. Figure a shows the morphological characteristics when the capillary pulls up the curved liquid surface after contacting the substrate, Figure b shows the dynamic morphology at a certain time point during the printing process, Figure c shows the structural morphology when the program is completed but the capillary has not been removed, and Figure d shows the final structural morphology formed after the capillary is removed.

[0054] Figure 4 SEM image of the printed micropillars.

[0055] Figure 5 This is a complete microtube printing process in an embodiment of the present invention, wherein the printing speed is 1.75 μm / s, the capillary diameter is 75 μm, the precursor mixture is a graphene oxide dispersion, and the nanoparticles are in the form of flakes. Figure a shows the morphological characteristics of the capillary when the curved liquid surface is pulled up after contacting the substrate, Figure b shows the dynamic morphology at a certain time point during the printing process, Figure c shows the structural morphology when the program is completed but the capillary has not been removed, and Figure d shows the final structural morphology formed after the capillary is removed.

[0056] Figure 6 SEM image of the printed microtubes.

[0057] Figure 1 The markings are as follows:

[0058] 1-program controller, 2-stepping motor driver, 3-XYZ three-axis moving mechanism, 4-capillary, 5-horizontal loading platform, 6-substrate, 7-multi-magnification optical microscope; DETAILED DESCRIPTION

[0059] A method for controlling the three-dimensional structure of a micro-nano device by pen-type direct writing 3D printing based on the shape of nanoparticles, comprising the following steps:

[0060] S1. According to the designed three-dimensional structure of the device to be printed, the three-dimensional model data is produced, and the sequence and slice information for printing are obtained;

[0061] S2. According to the designed three-dimensional structure of the device to be printed, a uniform precursor mixture of a corresponding nanoparticle shape is selected; illustratively, a microcolumn structure or a microtube structure is printed by selecting a spherical particle or a non-spherical particle precursor mixture.

[0062] S3. According to the designed three-dimensional structure size of the device to be printed, the substrate heating temperature value is selected to ensure that the substrate is heated to a suitable temperature, in order to accelerate the evaporation of the curved liquid surface contacting the substrate;

[0063] S4. Control the ambient humidity and ambient temperature to ensure the stability of the external environmental conditions during the printing process;

[0064] S5, transferring the precursor mixture in step S2 into the capillary. Before printing begins, the capillary is controlled to contact with the horizontal loading platform, and the height is adjusted until an initial curved liquid surface appears between the capillary outlet and the substrate.

[0065] S6. Based on the printing sequence of step S1, the slicing information and the initial curved liquid surface of step S5, the 3D printing process is moved and executed.

[0066] In some specific embodiments, in step S2, the precursor mixture is selected from any one or more solutions of aluminum oxide nanoparticles, titanium dioxide nanoparticles, graphene oxide nanoparticles, molybdenum trioxide nanoparticles, and PMMA / PPy composite nanoparticles.

[0067] When performing multi-material mixed printing, the present invention uses two or more different precursor mixtures in a single printing process, and by precisely controlling the printing path and deposition sequence of each mixture, a composite structure composed of multiple materials can be printed. For example, a mixture of spherical nanoparticles and non-spherical nanoparticles is alternately deposited to form an electronic device with a specific structure and function.

[0068] In some specific embodiments, the aluminum oxide nanoparticles and titanium dioxide nanoparticles are spherical in shape, and the graphene oxide nanoparticles, molybdenum trioxide nanoparticles and PMMA / PPy composite nanoparticles are non-spherical in shape.

[0069] In some specific embodiments, when the precursor mixed solution is an aluminum oxide nanoparticle solution, the aluminum oxide nanoparticles are spherical in shape, with a particle size of 10 to 20 nm, and a mass fraction of the solution is 15 to 25 wt %.

[0070] In some specific embodiments, when the precursor mixed solution is a titanium dioxide nanoparticle solution, the titanium dioxide nanoparticles are spherical in shape, with a particle size of 10 to 20 nm, and a mass fraction of the solution is 25 to 30 wt %.

[0071] In some specific embodiments, when the precursor mixture is a graphene oxide nanoparticle solution, the graphene oxide nanoparticles are in the shape of flakes, with a flake diameter of 0.1 to 10 μm and a thickness of 0.6 to 1 nm, and the concentration of the solution is 2-10 mg / mL.

[0072] In some specific embodiments, when the precursor mixture is a molybdenum trioxide nanoparticle solution, the molybdenum trioxide nanoparticles are rod-shaped with a diameter of 10 to 20 nm and a length of 100 to 150 nm, and the mass fraction of the solution is 0.5 to 20 wt%.

[0073] In some specific embodiments, when the precursor mixture is a PMMA / PPy composite nanoparticle solution, the PMMA / PPy composite nanoparticles are fibrous in shape with a diameter of 30-40 nm, the mass ratio of PMMA to PPy is 1:2.5, and the mass fraction of the solution is 15-20 wt%.

[0074] For example, the precursor mixture can be an aluminum oxide nano-solution with a concentration of 20 wt.% and a particle size of 10-20 nm. The precursor mixture can be a graphene oxide aqueous solution with a concentration of 5 mg / mL, a sheet diameter of 0.5-10 μm, and a thickness of 0.6-1 nm.

[0075] In some specific embodiments, in step S4, the ambient humidity is 50% to 60%, and the ambient temperature is room temperature.

[0076] In some specific embodiments, in step S5, the height of the initial meniscus between the outlet of the capillary and the substrate is in the range of 25 to 55 μm, and the longitudinal cross-section of the initial meniscus is an arc-shaped curve profile with larger sizes at the upper and lower ends and smaller sizes in the middle part, and the overall structure is similar to a cylinder, which can be seen in Figure 2 ,3 This initial curved liquid surface with this shape and height can ensure the smooth progress of the subsequent 3D printing process.

[0077] In some specific embodiments, when the nanoparticles in the precursor mixture are spherical in shape, the height of the initial meniscus between the capillary outlet and the substrate is in the range of 30 μm±5 μm, and the diameter of the initial meniscus is smaller than the inner diameter of the capillary.

[0078] In some specific embodiments, when the nanoparticles in the precursor mixture are non-spherical in shape, the height of the initial meniscus between the capillary outlet and the substrate is in the range of 50 μm±5 μm, and the diameter of the initial meniscus is smaller than the outer diameter of the capillary.

[0079] In some specific embodiments, in step S5, the contact angle between the substrate and the precursor mixture is 80°.

[0080] In some specific embodiments, in step S6, the 3D printing process also includes: starting printing from the bottom layer of the printing order, moving at a set speed and path, and the precursor mixture continues to flow out and deposit under the traction of the curved liquid surface until the printing is completed to form the required structure.

[0081] In some specific embodiments, the minimum speed of movement can be determined according to the subdivision of the stepper motor driver. For example, if a subdivision of 6400 is used, the minimum speed is 0.3 μm / s, and the available speeds include 0.3 μm / s, 0.6 μm / s, 0.9 μm / s, 1.2 μm / s, etc.; if a subdivision of 25600 is used, the minimum speed is 0.25 μm / s, and the available speeds include 0.25 μm / s, 0.5 μm / s, 0.75 μm / s, 1.0 μm / s, etc.

[0082] In some specific embodiments, when designing a program, it can be a single-dimensional micro-columnar (micro-tubular) structure formed by vertical deposition, or it can be a multi-dimensional (horizontal and vertical directions) collaborative operation to form other complex three-dimensional structures.

[0083] In some specific embodiments, 3D printing parameters are optimized, such as substrate heating temperature, contact height between the capillary and the substrate, and printing speed, to adapt to the deposition characteristics of nanoparticles of different shapes. For example, for non-spherical nanoparticles in the precursor mixture, a higher substrate heating temperature may be required to promote their flat arrangement on the substrate; while for spherical nanoparticles in the precursor mixture, a lower heating temperature may be required to maintain their fluidity. By adjusting these parameters, the printing process can be optimized to achieve precise control of the three-dimensional structure of micro-nano devices.

[0084] The present invention also provides a device for operating a method for controlling the three-dimensional structure of a micro-nano device by pen-type direct writing 3D printing based on the shape of nanoparticles, such as Figure 1 As shown, including:

[0085] A capillary 4 for containing the precursor mixture,

[0086] An XYZ three-axis moving mechanism 3 for moving the capillary 4 for 3D printing,

[0087] A stepper motor driver 2 drives the XYZ three-axis moving structure 3 to move the capillary 4,

[0088] A program controller 1 for controlling the moving speed of the stepper motor driver 2,

[0089] A horizontal loading platform 5 placed below the capillary 4 and used for the operation of the capillary 4,

[0090] A substrate 6 is placed on the horizontal loading platform,

[0091] Multi-magnification optical microscope used to observe 3D printed micro-nano devices7.

[0092] The diameter of the capillary 4 is 50-100 μm, and can be selected as 50 μm, 75 μm, or 100 μm, so as to obtain structures of various sizes within the range of 30-80 μm.

[0093] The substrate 6 is a 1 cm×1 cm square aluminum sheet with a thickness of 0.3 cm.

[0094] The program controller 1 is a programmable controller, such as a PLC controller.

[0095] In order to adapt to the deposition characteristics of nanoparticles of different shapes and optimize the printing process, the device also includes:

[0096] A temperature and humidity control mechanism for adjusting the ambient temperature and humidity, the temperature and humidity control mechanism comprising a humidifier, a dehumidifier, and a humidity detection probe;

[0097] A ceramic heating plate for heating the substrate 6, a voltage controller connected to the ceramic heating plate, and a thermocouple display for observing the temperature value at the substrate.

[0098] The above embodiments may be implemented individually or in any combination of two or more.

[0099] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0100] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0101] In conjunction with the accompanying drawings, some embodiments of the present invention are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0102] In the following embodiments, if there is no special description of functional components or structures, it means that they are all conventional components or conventional structures used in the art to achieve corresponding functions. If there is no special description of raw materials or processing techniques, it means that they are all conventional commercially available raw materials or conventional processing techniques in the art.

[0103] Embodiment 1:

[0104] Based on the above-mentioned device, this embodiment provides a 3D printed micro-column structure, using a spherical aluminum oxide nanoparticle solution, including the following steps:

[0105] (1) Obtain the three-dimensional model data of the microcolumn structure to be printed. The three-dimensional data model is designed by software such as SolidWorks. The program controller receives the printing sequence information and slicing information of the generated file model and layers the information from the bottom layer to the top layer. The substrate is the bottom layer of the processing surface, and the movement path of the capillary is consistent with the writing order and hierarchical information of each layer of structural features (from the first layer to the nth layer of the image).

[0106] (2) Turn on the humidity control mechanism (including humidifier, dehumidifier, and humidity detection probe). If you want to control the humidity range at 60% RH, you need to turn on the humidifier and spray it at a rate of 60 mL / h. Repeat the spraying process of working for 30 seconds and stopping for 30 seconds. At the same time, turn on the dehumidifier. The dehumidification upper limit of the dehumidifier is designed to be 63%, which means that dehumidification begins when the humidity detection probe detects that the ambient humidity reaches 63% RH. The dehumidification power is 40 W, and the dehumidification lower limit is 60%, which means that dehumidification stops when the ambient humidity reaches 60%.

[0107] In this embodiment, the ambient humidity is 60% and the ambient temperature is room temperature.

[0108] (3) Turn on the voltage controller connected to the ceramic heater. If you want to control the substrate temperature at 40°C, you need to adjust the voltage to 3.20V. Observe the temperature value at the substrate in real time through the thermocouple display and adjust it accordingly as needed.

[0109] In this embodiment, the substrate heating temperature is 40°C.

[0110] (4) Alumina nanoparticle solution is used as a precursor mixture, the concentration of the precursor mixture is 20wt.%, the particle size is 10-20nm, and the shape of the nanoparticles is spherical.

[0111] (5) Ultrasonicate the precursor mixture for 10 minutes to ensure that the precursor mixture is evenly dispersed. Then inject the evenly dispersed precursor mixture into the capillary (the diameter is selected to be 75μm), and fix the capillary on the three-dimensional XYZ displacement platform; adjust the vertical lifting platform to make the capillary lightly contact the substrate, and adjust until an initial curved liquid surface appears between the capillary outlet and the substrate, so that the height of the initial curved liquid surface is within the range of 30μm±5μm, and the maximum diameter of the initial curved liquid surface is smaller than the inner diameter of the capillary, and the contact angle between the substrate and the precursor mixture is 80°. Stop adjusting the vertical lifting platform, start the program controller in the above steps, and start printing according to the sequence of the structures to be printed and the slice information. In this embodiment, the running speed of the design program is 1.75μm / s.

[0112] During the printing process, no additional auxiliary tools are required, and the printed structure will be continuously deposited on the printing platform until the printing process is completed, forming a micro-columnar structure.

[0113] like Figure 2 As shown in A, it is a schematic diagram of the principle of printing the micro-column structure. When the precursor mixture comes into contact with the substrate, an initial curved liquid surface will be formed between the capillary outlet and the substrate under the action of surface tension. At this time, the nanoparticles in the precursor mixture in the initial curved liquid surface continue to deposit on the substrate and form a deposition front. As the deposition front continues to grow upward and the curved liquid surface continues to move upward with the capillary, the nanoparticles in the precursor mixture continue to deposit on the deposition front, causing the deposition front to continue to grow and eventually form a preset three-dimensional structure.

[0114] like Figure 3 Figure 2 shows the actual process of printing the microcolumn structure. Figure a shows the morphological characteristics when the capillary pulls up the curved liquid surface after contacting the substrate. Figure b shows the dynamic morphology at a certain time point during the printing process. Figure c is the structural morphology when the program is completed but the capillary has not been removed. Figure d shows the final structural morphology formed after the capillary is removed.

[0115] like Figure 4 Shown is the SEM image of the printed micropillars.

[0116] Embodiment 2:

[0117] Based on the above-mentioned device, this embodiment provides a 3D printed microtube structure, using a flake graphene oxide nanoparticle solution, including the following steps:

[0118] (1) Obtain the three-dimensional model data of the microtubule structure to be printed. The three-dimensional data model is designed by software such as SolidWorks. The program controller receives the printing sequence information and slicing information of the generated file model and layers the information from the bottom layer to the top layer. The substrate is the bottom layer of the processing surface, and the movement path of the capillary is consistent with the writing order and hierarchical information of each layer of structural features (from the first layer to the nth layer of the image).

[0119] (2) Turn on the humidity control mechanism (including humidifier, dehumidifier, and humidity detection probe). If you want to control the humidity range at 60% RH, you need to turn on the humidifier and spray it at a rate of 60 mL / h. Repeat the spraying process of working for 30 seconds and stopping for 30 seconds. At the same time, turn on the dehumidifier. The dehumidification upper limit of the dehumidifier is designed to be 63%, which means that dehumidification begins when the humidity detection probe detects that the ambient humidity reaches 63% RH. The dehumidification power is 40 W, and the dehumidification lower limit is 60%, which means that dehumidification stops when the ambient humidity reaches 60%.

[0120] In this embodiment, the ambient humidity is 60% and the ambient temperature is room temperature.

[0121] (3) Turn on the voltage controller connected to the ceramic heater. If you want to control the substrate temperature at 40°C, you need to adjust the voltage to 3.20V. Observe the temperature value at the substrate in real time through the thermocouple display and adjust it accordingly as needed.

[0122] In this embodiment, the substrate heating temperature is 40°C.

[0123] (4) GO nano-solution was used as the precursor mixture, the concentration of the precursor mixture was 5 mg / mL, the flake diameter was 0.5-10 μm, and the nanoparticle shape was flake-shaped.

[0124] (5) Ultrasonicate the precursor mixture for 10 minutes to ensure that the precursor mixture is evenly dispersed. Then inject the evenly dispersed precursor mixture into the capillary (the diameter is selected to be 75μm), and fix the capillary on the three-dimensional XYZ displacement platform; adjust the vertical lifting platform to make the capillary lightly contact the substrate, and adjust it until a curved liquid surface appears between the capillary outlet and the substrate, and the contact angle between the substrate and the precursor mixture is 80°. Stop adjusting the vertical lifting platform, and start the program controller in the above steps to start printing according to the sequence of the structure to be printed and the slice information. In this embodiment, the running speed of the design program is 1.75μm / s.

[0125] During the printing process, no additional auxiliary tools are required, and the printed structure will be continuously deposited on the printing platform until the printing process is completed, forming a microtubular structure.

[0126] like Figure 2FIG. 3 is a schematic diagram of the principle of printing the microtube structure as described above. FIG.

[0127] like Figure 5 Figure 2 shows the actual process of printing the microtube structure. Figure a shows the morphological characteristics when the capillary pulls up the curved liquid surface after contacting the substrate. Figure b shows the dynamic morphology at a certain time point during the printing process. Figure c is the structural morphology when the program is completed but the capillary has not been removed. Figure d shows the final structural morphology formed after the capillary is removed.

[0128] like Figure 6 Shown is the SEM image of the printed microtubule structure.

[0129] Embodiment 3:

[0130] Compared with Example 1, most of them are the same, the only difference is that the spherical aluminum oxide nanoparticle solution is replaced by a spherical titanium dioxide nanoparticle solution as the precursor mixture, wherein the particle size of the spherical titanium dioxide nanoparticles is 10 to 20 nm, the mass fraction is 25wt%, and the microcolumn structure is obtained by 3D printing.

[0131] Embodiment 4:

[0132] Compared with Example 2, most of them are the same, the only difference is that the flaky graphene oxide nanoparticle solution is replaced by a rod-shaped molybdenum trioxide nanoparticle solution as a precursor solution, wherein the rod-shaped molybdenum trioxide nanoparticles have a diameter of 10 to 20 nm and a length of 100 to 150 nm, and the mass fraction of the solution is 10wt%, and microtubes are obtained by 3D printing.

[0133] Embodiment 5:

[0134] Compared with Example 2, most of them are the same, the only difference is that the flaky graphene oxide nanoparticle solution is replaced by a fibrous PMMA / PPy composite material nanoparticle solution as a precursor solution, wherein the diameter of the fibrous PMMA / PPy composite material nanoparticles is 30-40nm, the mass ratio of PMMA to PPy is 1:2.5, the mass fraction of the solution is 16wt%, and microtubes are obtained by 3D printing.

[0135] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for controlling the three-dimensional structure of micro-nano devices by pen-type direct writing 3D printing based on the shape of nanoparticles, characterized in that: The steps include: S1. Determine the 3D printing sequence, slicing information, and substrate heating temperature of the device to be printed; S2, placing the precursor mixture for 3D printing the device to be printed in the capillary, and adjusting the height so that an initial curved liquid surface appears between the outlet of the capillary and the substrate, Wherein, the precursor mixture is a solution containing spherical nanoparticles or non-spherical nanoparticles; S3, based on the 3D printing sequence and slicing information determined in step S1, and the initial curved liquid surface in step S2, the ambient humidity and ambient temperature are adjusted, and the 3D printing process is performed by moving.

2. The method according to claim 1, characterized in that In step S2, the precursor mixture is a solution of any one or more selected from aluminum oxide nanoparticles, titanium dioxide nanoparticles, graphene oxide nanoparticles, molybdenum trioxide nanoparticles, and PMMA / PPy composite nanoparticles.

3. The method according to claim 2, characterized in that The aluminum oxide nanoparticles and titanium dioxide nanoparticles are spherical in shape, and the graphene oxide nanoparticles, molybdenum trioxide nanoparticles and PMMA / PPy composite material nanoparticles are non-spherical in shape.

4. The method according to claim 2, characterized in that: When the precursor mixed solution is an aluminum oxide nanoparticle solution, the aluminum oxide nanoparticles are spherical in shape, with a particle size of 10 to 20 nm, and a mass fraction of the solution of 15 to 25 wt %; When the precursor mixed solution is a titanium dioxide nanoparticle solution, the titanium dioxide nanoparticles are spherical in shape, with a particle size of 10 to 20 nm, and the mass fraction of the solution is 25 to 30 wt %.

5. The method according to claim 2, characterized in that: When the precursor mixture is a graphene oxide nanoparticle solution, the graphene oxide nanoparticles are in the form of flakes, with a flake diameter of 0.1 to 10 μm and a thickness of 0.6 to 1 nm, and the concentration of the solution is 2 to 10 mg / mL; When the precursor mixture is a molybdenum trioxide nanoparticle solution, the molybdenum trioxide nanoparticles are rod-shaped, with a diameter of 10 to 20 nm and a length of 100 to 150 nm, and the mass fraction of the solution is 0.5 to 20 wt %; When the precursor mixture is a PMMA / PPy composite nanoparticle solution, the PMMA / PPy composite nanoparticle is fibrous in shape with a diameter of 30-40 nm, and the mass ratio of PMMA to PPy is 1: 2.5, the mass fraction of the solution is 15-20wt%.

6. The method according to claim 1, characterized in that In step S2, the height of the initial curved liquid surface between the outlet of the capillary and the substrate ranges from 25 to 55 μm, and the longitudinal section of the initial curved liquid surface presents an arc-shaped curve profile with large dimensions at the upper and lower ends and a small dimension in the middle, and the overall structure is similar to a cylinder.

7. The method according to claim 6, characterized in that When the nanoparticles in the precursor mixture are spherical in shape, the height range of the initial meniscus between the outlet of the capillary and the substrate is 30 μm±5 μm, and the maximum diameter of the initial meniscus is smaller than the inner diameter of the capillary; When the nanoparticles in the precursor mixture are non-spherical in shape, the height range of the initial meniscus between the outlet of the capillary and the substrate is 50 μm±5 μm, and the maximum diameter of the initial meniscus is smaller than the outer diameter of the capillary.

8. The method according to claim 6, characterized in that In step S2, the contact angle between the substrate and the precursor mixture is 80°; In step S3, the ambient humidity is 50% to 60%, and the ambient temperature is room temperature; In step S3, the 3D printing process also includes: starting printing from the bottom layer of the printing order, moving at a set speed and path, and the precursor mixture continues to flow out and deposit under the traction of the curved liquid surface until the printing is completed to form the required structure.

9. A 3D printed microcolumn, characterized in that: Based on the method described in any one of claims 1 to 8, the precursor mixed solution is selected from any one or more of a spherical aluminum oxide nanoparticle solution and a spherical titanium dioxide nanoparticle solution.

10. A 3D printed microtube, characterized in that: Based on the method described in any one of claims 1 to 8, the precursor mixture is selected from any one or more of a flaky graphene oxide nanoparticle solution, a rod-shaped molybdenum trioxide nanoparticle solution, and a fibrous PMMA / PPy composite material nanoparticle solution.

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