All-dielectric structure type broadband wave-absorbing metamaterial and design method thereof

Abstract

The invention discloses an all-dielectric structure type broadband wave-absorbing metamaterial and a design method thereof. The all-dielectric structure type broadband wave-absorbing metamaterial comprises a substrate and a plurality of resonators, the plurality of resonators are periodically and uniformly arrayed on the surface of the substrate, the adjacent resonators are connected with each other, each resonator comprises a pyramid structure unit and a grid structure unit, the pyramid structure units are nested in the grid structure units to form a pyramid-grid composite resonator, and the substrate and the resonators are both made of a high dielectric loss composite material. Based on the brand new design angle of wave absorbing performance complementation, the limitation of the wave absorbing performance of a single structure is broken through, the wave absorbing performance is improved from the microstructure level, meanwhile, efficient electromagnetic wave energy absorption is achieved in a wider frequency range, multi-stage dissipation and broadband impedance matching of incident electromagnetic waves are achieved, and the wave absorbing performance is improved. And the technical limitation of thickness constraint and narrow-band response of the traditional wave-absorbing material is broken through.

Description

Technical Field

[0001] The present invention belongs to the field of information technology, and in particular to an all-dielectric structured broadband wave-absorbing metamaterial and a design method thereof. Background Art

[0002] Metamaterial absorbers are artificially designed electromagnetic metamaterials that achieve efficient absorption of electromagnetic waves through structural design and material configuration. These materials have garnered widespread attention in recent years due to their remarkable electromagnetic wave control capabilities. Compared to traditional absorbers, metamaterials offer advantages such as high designability, lightweight, high absorption efficiency, and strong structural controllability. Their performance is optimized primarily through their microstructures, reducing electromagnetic wave reflection and leakage, lowering electromagnetic interference, and playing a significant role in improving the electromagnetic compatibility (EMC) of electronic equipment, power systems, and communications devices. Furthermore, in the field of stealth technology, metamaterials are widely used in radar stealth technology for aerospace, naval vessels, and military applications, significantly enhancing stealth performance. Broadband absorption is a key area of performance optimization for absorbing metamaterials, meaning they can efficiently absorb electromagnetic waves across a wide frequency range. Compared to narrowband absorbers, broadband absorbers offer greater applicability and practicality.

[0003] Absorbing materials can be categorized as traditional, sandwich metamaterials, and all-dielectric metamaterials. These three categories differ significantly in their operating principles, design structures, and performance characteristics. Traditional absorbing materials primarily rely on the material's inherent electromagnetic properties to absorb electromagnetic wave energy. Common materials include ferrites and carbon-based materials. Their primary drawbacks are their thickness and weight, making them unsuitable for applications where mass and thickness are critical, such as aviation. Furthermore, their poor designability makes them difficult to meet the demands of sophisticated stealth and high performance. Sandwich metamaterials employ a layered design, typically combining metal or electromagnetically responsive materials on top and bottom layers with an electromagnetically lossy dielectric in the middle. This creates a composite structure. Compared to traditional absorbing materials, sandwich metamaterials offer higher absorption efficiency, superior broadband absorption, and controllable structure, allowing for greater design freedom and adaptability to multi-band requirements. However, their primary drawbacks are the complex manufacturing process, high cost, and overall density, making them unsuitable for certain applications requiring ultra-thinness. All-dielectric absorbing metamaterials are composed entirely of dielectric materials, eliminating the need for metal layers and relying on a gradient design of dielectric constant and magnetic permeability to achieve wave absorption. Their advantages include light weight and thin thickness, making them suitable for the aerospace industry, where weight control is critical. They also offer low loss, no eddy current losses caused by metal, minimal thermal effects, and high designability, making them suitable for multi-band wave absorption. However, current research into all-dielectric absorbing metamaterials still faces challenges in processing and manufacturing. Their heavy reliance on micro-nanofabrication technology makes manufacturing expensive, and the significant influence of the dielectric's electromagnetic parameters on their absorbing properties makes them difficult to control. Summary of the Invention

[0004] The purpose of the present invention is to provide a full-dielectric structure broadband absorbing metamaterial and a design method thereof, so as to solve the problems of difficulty in processing, manufacturing and regulating existing full-dielectric absorbing metamaterials.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A broadband absorbing metamaterial with an all-dielectric structure, comprising a substrate and a plurality of resonators; Several resonators are periodically and uniformly arrayed on the surface of a substrate. Adjacent resonators are interconnected. The resonators include pyramid structure units and grid structure units. The pyramid structure units are nested in the grid structure units to form a pyramid-grid composite resonator. Both the substrate and the resonator are made of high dielectric loss composite materials.

[0006] Furthermore, the absorption frequency band of the metamaterial is 3.2~18GHz.

[0007] Furthermore, the dielectric material of the metamaterial is conductive graphite powder, and the purity of the conductive graphite powder is ≥99.9%.

[0008] Furthermore, the substrate and the resonator are an integrally formed structure.

[0009] Furthermore, the height of the pyramid structure unit is greater than the height of the grid structure unit.

[0010] Furthermore, there are gaps between the pyramid structure units and the grid structure units.

[0011] A design method for the all-dielectric structure broadband absorbing metamaterial includes: Preparation of high dielectric loss composite materials; Through three-dimensional parametric modeling and electromagnetic simulation, a full-wave simulation model under periodic boundary conditions is constructed; Based on the full-wave simulation model, the time-domain finite element algorithm is used to simulate and optimize the structural parameters of the metamaterial; According to the optimized metamaterial structural parameters, the prepared high dielectric loss composite material is used for three-dimensional molding processing.

[0012] Furthermore, a method for preparing a high dielectric loss composite material comprises: ABS polymer plastic particles and high-purity conductive graphite powder are mixed in a mass ratio of 1:1 and evenly dispersed using a twin-screw mixer; The blending is carried out by melt extrusion at a temperature of 150-180°C, and the standard wire is formed by drawing and water cooling.

[0013] Furthermore, the metamaterial structural parameters include the period of the resonator array, the upper base width, lower base width and height of the pyramid structure unit, the width and height of the grid structure unit and the height of the base.

[0014] Furthermore, three-dimensional forming processing methods include micro-nano machining and 3D printing processes.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a fully dielectric, broadband absorbing metamaterial. This material utilizes a high-dielectric loss composite material as the dielectric material. By nesting pyramid structural units within lattice structural units, a pyramid-lattice composite resonator is formed. Several resonators are periodically and uniformly arrayed on the surface of a substrate, with adjacent resonators interconnected. Based on a novel design approach based on complementary absorption properties, this invention overcomes the limitations of single-structure absorption performance and effectively addresses the issue of insufficient broadband absorption capacity. The two structures are nested together to form a novel, highly efficient absorbing metamaterial. This not only improves absorption performance at the microstructural level, but also achieves efficient electromagnetic wave energy absorption over a wider frequency range, demonstrating excellent broadband microwave absorption. Through the electromagnetic synergy of multi-scale geometric configurations, it achieves an average absorption rate exceeding 95% within an ultra-wideband frequency band of 3.2 to 18 GHz. This achieves multi-stage dissipation of incident electromagnetic waves and broadband impedance matching, overcoming the technical limitations of traditional absorbing materials, which are limited by thickness and narrowband response. This provides a new theoretical foundation and technical support for the research and application of fully dielectric absorbing metamaterials. It has demonstrated significant technical advantages in areas such as electromagnetic compatibility protection (EMC) and multi-band communication anti-interference, providing an engineering-implementable solution for the new generation of high-performance absorbing material systems, and has broad practical application prospects.

[0016] The present invention also provides a design method for an all-dielectric structured broadband absorbing metamaterial. This method uses a time-domain finite element method to perform electromagnetic simulation calculations on the model. Combined with a particle swarm optimization (PSO) algorithm, the method uses the final microwave absorption effect as the objective function to perform a joint simulation of logic programming and electromagnetic calculations. The method further optimizes the structural dimensional parameters, gradually adjusting and optimizing the dimensions and combinations of each structural parameter to ultimately achieve the optimal absorbing effect. The specific dimensions of each parameter are clearly defined, thereby achieving high-efficiency performance of the all-dielectric absorbing metamaterial across a wide frequency range. Ultimately, a fully dielectric absorbing metamaterial with excellent broadband absorbing performance is obtained. This method, combined with the design method of a high-efficiency absorbing metamaterial model, significantly improves the absorbing effect of the all-dielectric absorbing metamaterial. By optimizing the parameters and determining the optimal parameter combination, the method successfully achieves efficient and stable broadband absorbing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is a diagram of the complex dielectric constant of the substrate in Example 1 of the present invention.

[0019] Figure 2 Schematic diagram of the pyramid-lattice metamaterial structure unit in Example 1 of the present invention.

[0020] Figure 3 This is a graph showing the calculation results of the absorption rate of the pyramid-grid metamaterial structure in Example 1 of the present invention.

[0021] Figure 4 This is a diagram of the pyramid-lattice metamaterial sample prepared in Example 1 of the present invention.

[0022] Figure 5 2 is a comparison chart of the test and simulation results in Example 1 of the present invention.

[0023] Among them: 1-matrix, 2-pyramid structure unit, 3-grid structure unit. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0026] 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, it does not need to be further defined or explained in subsequent drawings.

[0027] In the description of the embodiments of the present invention, it should be noted that if the terms "upper," "lower," "horizontal," "inner," etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the inventive product is typically placed when in use. These terms are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0028] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0029] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0030] The present invention is described in further detail below with reference to the accompanying drawings: The present invention provides a broadband absorbing metamaterial with an all-dielectric structure, comprising a substrate 1 and a plurality of resonators. The substrate and the resonators are an integrally formed structure. The integrally formed structure can effectively reduce gaps and connection points in the structure, reduce the reflection and scattering of electromagnetic waves during propagation, and thus improve the absorbing performance of the metamaterial. The plurality of resonators are periodically and uniformly arrayed on the surface of the substrate 1, and adjacent resonators are interconnected. This periodic and uniform array layout enables the metamaterial to produce a regular response to incident electromagnetic waves, forming a specific electromagnetic resonance mode, thereby enhancing the absorption effect of electromagnetic waves. The resonator comprises a pyramid structure unit 2 and a grid structure unit 3. The pyramid structure unit 2 is nested in the grid structure unit 3 to form a pyramid-grid composite resonator. The height of the pyramid structure unit 2 is greater than the height of the grid structure unit 3, and a gap exists between the pyramid structure unit 2 and the grid structure unit 3. This enables the pyramid structure unit 2 to effectively capture and scatter incident electromagnetic waves. When an electromagnetic wave is incident on the pyramid structure unit 2, its inclined surface will reflect and refract the electromagnetic wave multiple times, increasing the propagation path of the electromagnetic wave inside the material, thereby increasing the interaction time between the electromagnetic wave and the material, which is beneficial to the absorption of electromagnetic wave energy. The grid structure unit 3 can generate electromagnetic resonance and convert the energy of the electromagnetic wave into other forms of energy. The gap between the pyramid structure unit 2 and the grid structure unit 3 not only provides space for the propagation and interaction of electromagnetic waves, but also realizes the synergistic optimization of the wave absorption characteristics of the two structures through the electromagnetic coupling effect between heterogeneous structures. The metamaterial structure of the present invention combines the two wave absorption structures of the grid and the pyramid, fully utilizes the respective wave absorption characteristics of the two structures, and synergistically optimizes them through the electromagnetic coupling effect between heterogeneous structures. At the same time, it effectively solves the absorption defect problem that exists when the two are used alone, and realizes multi-level dissipation and broadband impedance matching of the incident electromagnetic wave.

[0031] Both the substrate and the resonator are made of a high-dielectric loss composite material. This material converts electromagnetic wave energy into heat under the influence of an electromagnetic field, thereby achieving wave absorption. In this invention, the metamaterial's dielectric material is conductive graphite powder with a purity of ≥99.9%. This high-purity conductive graphite powder has a more uniform microstructure and more stable electromagnetic properties, ensuring the metamaterial maintains stable wave absorption under various environmental conditions.

[0032] The present invention also provides a design method for a full-dielectric structure broadband absorbing metamaterial, comprising: First, a matrix composite material with high dielectric loss characteristics is prepared to provide a material basis for the wave absorbing function: ABS polymer plastic particles and high-purity conductive graphite powder are mixed in a mass ratio of 1:1 and evenly dispersed using a twin-screw mixer; The blending is carried out at a temperature of 150-180℃ and then melt-extruded, and then the standard wire is formed by water cooling and drawing; Then, through three-dimensional parametric modeling and electromagnetic simulation, a full-wave simulation model under periodic boundary conditions is constructed. Based on the full-wave simulation model, the time-domain finite element method is used to simulate and optimize the structural parameters of the metamaterial. Based on this, micro-nano machining or 3D printing technology is used to perform three-dimensional molding processing based on the optimized pyramid-lattice structure parameters. The metamaterial structural parameters include the period of the resonator array, the upper base width, lower base width and height of the pyramid structure unit, the width and height of the lattice structure unit, and the height of the base. Finally, the sample's wide-band (2~18GHz) absorption performance was characterized through a microwave anechoic chamber reflectivity test system. The deviation between the measured absorption rate and the simulation prediction value was verified to verify the effectiveness of the structural design and processing technology, forming a complete technical chain from material development, structural manufacturing to performance verification.

[0033] The present invention is described in further detail below through specific embodiments: Example 1: The design method of the all-dielectric structure broadband absorbing metamaterial of this embodiment includes: Step 1: Design and preparation of high dielectric loss composite materials 1.1 Material system selection Matrix material: ABS polymer plastic particles (thermoplastic engineering plastics).

[0034] Loss agent material: high-purity conductive graphite powder (purity ≥99.9%).

[0035] Mass ratio: The matrix material and the loss agent are compounded in a 1:1 mass ratio.

[0036] 1.2 Preparation process Premixing: Use a twin-screw mixer for dry mixing to ensure uniform dispersion of the materials.

[0037] Melt extrusion: blending and melting are carried out at a temperature range of 170°C.

[0038] Wire forming: The wire is shaped into 2.85±0.05mm standard wire through a water-cooled pulling system.

[0039] 1.3 Sample preparation Test sample: Standard waveguide test sample (22.85 * 10.16 * 2.0 mm) prepared using FDM 3D printing technology Electromagnetic characteristics characterization: Use vector network analyzer to perform X-band (8.2~12.4GHz) testing, such as Figure 1 As shown, the real part of the complex dielectric constant (ε'): 16.2±0.2, the imaginary part of the complex dielectric constant (ε''): 3.9±0.2, and the dielectric loss tangent (tanδ): 0.23±0.02. Test data shows that ε' and ε'' maintain high, stable, and strong loss characteristics in the X-band, and the stable loss performance of tanδ>0.2 meets the electromagnetic parameter requirements of all-dielectric absorbing metamaterials for high-loss dielectric substrates. Through component optimization and innovative preparation processes, this composite material system successfully achieves the coordinated control of 3D printing compatibility and electromagnetic loss properties, providing an ideal material foundation for subsequent metamaterial structure design.

[0040] Step 2: Metamaterial structure design Based on the composite material prepared in step 1, a full dielectric metamaterial, a pyramid-grid composite structure, is designed. The structural units are as follows: Figure 2 As shown, its geometric features are defined by parametric variables, including the resonator array period P, the upper base width L1, lower base width L2, and height H3 of pyramid structure unit 2, the width W and height H2 of lattice structure unit 3, and the height H1 of base 1. After completing 3D parametric modeling in SolidWorks or 3ds Max, the measured complex dielectric constants (real and imaginary parts ε'') of the composite material were imported into CST Studio Suite or HFSS electromagnetic simulation software to construct a full-wave simulation model under periodic boundary conditions. Using a time-domain finite element method combined with perfectly matched layer (PML) boundary conditions and a broadband Gaussian pulse wave as the excitation source, the reflectivity R and transmittance T (T = 0 for a metal backplane) were calculated. The absorption performance of the structure in the 2-18 GHz frequency range was quantified using the absorptivity formula A = 1-RT.

[0041] Step 3: Structural improvement and performance optimization Based on extensive simulation calculations and analysis of the structural fabrication process's accuracy, the resonator's period, P, was determined to be 30 mm, and the lower base width, L2, of pyramid unit 2 was fixed at 16 mm. To improve absorption performance, electromagnetic simulation was combined with a particle swarm optimization (PSO) algorithm. An optimization model with absorptivity as the objective function was constructed using the Python / Matlab platform. The upper base width, L1, of pyramid unit 2, the width, W, of lattice unit 3, the height, H1, of base 1, the height, H2, of lattice unit 3, and the height, H3, of pyramid unit 2 were selected as the variables to be optimized. Boundary constraints were set based on the electromagnetic response characteristics of each parameter listed in Table 1, transforming the parameter optimization problem into a global optimization solution within a five-dimensional space. Through iterative calculations combined with electromagnetic simulation, the optimal parameter combination that achieves broadband absorption characteristics was obtained, as shown in Table 2. Combined with precision machining capabilities, the optimization results were uniformly accurate to the order of 0.1 mm.

[0042] Table 1 Parameter optimization interval

[0043] Table 2 Metamaterial structural parameters after optimization

[0044] Step 4: Simulation results analysis Based on the electromagnetic parameters of the material in step 1 and the optimized structural dimensions in step 3, full-wave numerical simulation of the metamaterial is performed using joint modeling software and electromagnetic simulation tools. Figure 3 As shown, the material exhibits excellent absorption performance across a wide frequency range of 3.2 to 18 GHz, with an average absorption rate of 95%, and consistently above 87% across the entire frequency band. Simulation data demonstrates that the optimized metamaterial achieves both high efficiency and strong stability in broadband microwave absorption, meeting the performance requirements for broadband absorbers in engineering applications.

[0045] Step 5: Sample preparation and experimental testing Based on the composite material and pyramid-lattice structure parameters designed by this invention, a highly efficient absorbing metamaterial prototype was fabricated via 3D printing. The prototype demonstrated stable absorption characteristics in a microwave anechoic chamber reflectivity test system. The actual absorption rate calculated from the measured reflectivity data matched the simulation results, confirming the structure's high absorption efficiency and applicability across a wide frequency band.

[0046] This embodiment uses the fused deposition modeling (FDM) 3D printing process, and the specific implementation process is as follows: First, the optimized metamaterial structure 3D model is imported into the printing system; the high dielectric loss composite wire prepared in step 1 is used as the printing consumables, and the parameters such as printing speed (50mm / s), nozzle temperature (260℃) and platform temperature (100℃) are precisely controlled to ensure that the structural dimensional accuracy error is ≤0.1mm, and the surface of the molded sample with smooth and defect-free surface is achieved. Figure 4 Finally, the reflectivity of the 2~18GHz frequency band was tested in a microwave darkroom using the bow method, and the test results were compared with the simulation results. Figure 5 As shown in the figure, the measured absorption rate curve is consistent with the simulation results (due to experimental environment problems and the small size of the overall sample preparation, there are errors in the low-frequency part below 6 GHz), verifying the reliability of the FDM process in the preparation of complex metamaterial structures and the effectiveness of design simulation.

[0047] By analyzing reflectivity experimental data and simulation results, the present invention demonstrates that this all-dielectric absorbing metamaterial achieves an average absorption rate of 95% in the 3.2-18 GHz band, while maintaining an overall thickness of only 10 mm. The minimum absorption rate within this frequency band is no less than 87%, achieving industry-leading absorption performance. Comprehensive analysis of experimental test data and theoretical analysis confirms that the metamaterial designed in this invention is a truly high-performance, broadband absorbing metamaterial, providing a practical reference for the practical production and application of absorbing metamaterials.

[0048] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A broadband absorbing metamaterial with an all-dielectric structure, characterized in that: comprising a substrate and a plurality of resonators; Several resonators are periodically and uniformly arrayed on the surface of a substrate. Adjacent resonators are interconnected. The resonators include pyramid structure units and grid structure units. The pyramid structure units are nested in the grid structure units to form a pyramid-grid composite resonator. Both the substrate and the resonator are made of high dielectric loss composite materials.

2. The all-dielectric structured broadband absorbing metamaterial according to claim 1, characterized in that: The absorption frequency band of metamaterials is 3.2~18GHz.

3. The all-dielectric structured broadband absorbing metamaterial according to claim 1, characterized in that: The dielectric material of the metamaterial is conductive graphite powder, and the purity of the conductive graphite powder is ≥99.9%.

4. The all-dielectric structured broadband absorbing metamaterial according to claim 1, characterized in that: The substrate and the resonator are an integrally formed structure.

5. The all-dielectric structured broadband absorbing metamaterial according to claim 1, characterized in that: The height of the pyramid structure unit is greater than the height of the grid structure unit.

6. The all-dielectric structured broadband absorbing metamaterial according to claim 1, characterized in that: There are gaps between the pyramid structure units and the grid structure units.

7. A design method for the all-dielectric structure broadband absorbing metamaterial according to any one of claims 1 to 6, characterized in that: include: Preparation of high dielectric loss composite materials; Through three-dimensional parametric modeling and electromagnetic simulation, a full-wave simulation model under periodic boundary conditions is constructed; Based on the full-wave simulation model, the time-domain finite element algorithm is used to simulate and optimize the structural parameters of the metamaterial; According to the optimized metamaterial structural parameters, the prepared high dielectric loss composite material is used for three-dimensional molding processing.

8. The design method of the all-dielectric structure broadband absorbing metamaterial according to claim 7, characterized in that: A method for preparing a high dielectric loss composite material, comprising: ABS polymer plastic particles and high-purity conductive graphite powder are mixed in a mass ratio of 1:1 and evenly dispersed using a twin-screw mixer; The blending is carried out by melt extrusion at a temperature of 150-180°C, and the standard wire is formed by drawing and water cooling.

9. The design method of the all-dielectric structure broadband absorbing metamaterial according to claim 7, characterized in that: The metamaterial structural parameters include the period of the resonator array, the upper base width, lower base width and height of the pyramid structure unit, the width and height of the grid structure unit and the height of the base.

10. The design method of the all-dielectric structure broadband absorbing metamaterial according to claim 7, characterized in that: Three-dimensional forming processing methods include micro-nano machining and 3D printing technology.

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