Preparation method of metamaterial wave absorber based on PDMS (Polydimethylsiloxane) micro-channel filled with liquid metal

Abstract

The invention discloses a preparation method of a metamaterial wave absorber filled with liquid metal based on a PDMS micro-channel, and the preparation method comprises the following steps: placing a PDMS film on a three-axis displacement platform by using a built femtosecond laser processing system, regulating and controlling the Z axis of the three-axis displacement platform through a computer, enabling femtosecond laser to be concentrated on the surface of the PDMS film, and processing the PDMS micro-channel by using the femtosecond laser processing system; processing a micro-channel with a star-shaped unit structure on the surface of the PDMS film through a processing path set in a computer; spin-coating PDMS colloid on the surface of the unprocessed PDMS film, and heating to semi-cure the PDMS colloid; covering the surface of the processed PDMS film with a semi-cured PDMS film, and heating and curing; and liquid metal is injected into the micro-channel of the star-shaped unit structure, and channels at the two ends are sealed. The preparation method combines laser precise processing, micro-channel design and adjustability of liquid metal, and has remarkable advantages.

Description

Technical Field

[0001] The present invention relates to the field of metamaterial absorbers, and in particular to a method for preparing a metamaterial absorber based on PDMS microchannels filled with liquid metal. Background Art

[0002] Metamaterial absorbers are a class of highly efficient electromagnetic wave absorbing materials based on artificial microstructures. By precisely controlling the dielectric constant, magnetic permeability, and microstructure dimensions of the material, they achieve efficient absorption of electromagnetic waves at specific frequencies. Their core mechanisms include electromagnetic resonance, impedance matching optimization, and multilayer or gradient structural design, resulting in superior absorption efficiency, bandwidth control, and thickness optimization compared to traditional absorbers. Traditional absorbers, such as ferrites and carbon-based materials, are typically thick and heavy, making it difficult to achieve both broadband absorption and flexibility, primarily due to limitations in their intrinsic properties and structural design. Broadband absorption typically relies on the material's strong dissipation of electromagnetic waves and multiple loss mechanisms, such as dielectric loss, magnetic loss, and impedance matching. However, many highly efficient absorbers (such as magnetic materials and conductive polymer composites) are often rigid or brittle, making them difficult to adapt to the demands of flexible devices. Flexible absorbers, on the other hand, typically employ polymer-based composites or low-density structures to provide good mechanical flexibility. However, this often sacrifices their strong electromagnetic wave absorption capacity, resulting in a narrower absorption bandwidth or reduced absorption efficiency. Metamaterial absorbers, with their ultrathin, lightweight, broadband, and efficient absorption properties, show broad application prospects in areas such as radar stealth, electromagnetic compatibility, 5G / 6G communications, wireless power transmission, and wearable electronic devices. Typical metamaterial absorber structures include resonant unit-based absorbers, metasurface absorbers, broadband metamaterial absorbers, and tunable metamaterial absorbers. Resonant unit-based absorbers achieve high absorption rates by creating local resonances through periodic structures such as metal patches and split resonant rings. Metasurface absorbers utilize two-dimensional metamaterial structures, achieving lightweight and flexibility through their ultrathin properties. Broadband metamaterial absorbers employ multilayer composite structures or gradient dielectric constant control to achieve broadband absorption. Tunable metamaterial absorbers utilize liquid crystals, MEMS, phase-change materials, and other techniques to manipulate their electromagnetic properties, enabling dynamic adjustment of the absorption frequency band. In the future, intelligent tunable absorbing technology, ultra-wideband absorbing materials, low-cost large-scale manufacturing processes, multi-physics field coupling metamaterials, etc. will become research hotspots, promoting the further application and development of metamaterial absorbers in stealth technology, electromagnetic protection, smart wearable devices and other fields.

[0003] At present, metamaterial absorbers still face technical challenges in combining flexibility with broadband absorption performance, and existing preparation methods often need to strike a balance between the two. The preparation methods of metamaterial absorbers cover a variety of advanced micro-nano processing technologies to achieve characteristics such as efficient electromagnetic wave absorption, lightweight, flexibility, and broadband regulation. Currently common preparation methods include photolithography, laser direct writing, 3D printing, sputtering deposition and etching, soft template transfer, spray self-assembly, and liquid metal microfluidic channel manufacturing. Photolithography processing technology mainly uses ultraviolet lithography or electron beam lithography to prepare high-precision periodic microstructures on the substrate material, which is suitable for high-frequency metamaterial absorbers in the millimeter wave and terahertz bands, but the cost is high and it is limited to small-area manufacturing; laser direct writing processing uses femtosecond or picosecond lasers to directly etch the surface of the material, which can realize microstructure processing on flexible substrates and is suitable for the preparation of flexible absorbers. It has the advantages of being fast and customizable; 3D printing technology constructs complex three-dimensional absorbing structures through selective laser sintering (SLS) or fused deposition (FDM), which is suitable for broadband absorbers and aviation. Low-frequency stealth materials are used in the aerospace field, but their resolution is limited. Sputtering deposition combined with dry or wet etching processes can deposit high-precision metal or dielectric layers on substrate surfaces, enabling the preparation of nanoscale metamaterial absorbers, suitable for semiconductor integrated absorbing chips. Soft template transfer technology uses elastic materials such as PDMS to transfer microstructures from a master to a target substrate, suitable for the preparation of flexible wearable absorbers, with low cost and suitable for large-scale production. Spray coating and self-assembly processes form periodic absorbing structures by depositing nanoparticles, carbon-based materials, or graphene, suitable for low-cost electromagnetic shielding materials, but uniformity is difficult to control. With the continuous advancement of manufacturing technology, the processing technology of metamaterial absorbers will develop towards high precision, low cost, flexibility, and tunability in the future. Combined with adaptive metamaterials, intelligent optimization design, and new materials, their application value will be more extensive in stealth technology, electromagnetic compatibility, 5G / 6G communications, aerospace, and wearable electronic devices.

[0004] Although micro-nano fabrication technologies such as photolithography, sputtering deposition, 3D printing, and laser direct writing can achieve efficient absorbing structures, they have certain limitations in terms of adaptability on flexible substrates, processing costs, and large-scale manufacturing capabilities. While methods such as soft template transfer, spray self-assembly, and liquid metal microfluidics are suitable for the manufacture of flexible devices, ensuring their stable absorption of electromagnetic waves over a wide frequency band remains a key challenge. Therefore, there is still a lack of a simple and reliable method that can simultaneously give metamaterial absorbers broadband absorption capabilities and excellent flexibility. This problem urgently needs to be overcome through new materials, new processes, and intelligent optimization design to promote the application of metamaterials in electromagnetic stealth, smart wearable devices, flexible electronics, and other fields. Summary of the Invention

[0005] To address the aforementioned issues in existing technologies, the present invention provides a method for fabricating a metamaterial absorber based on PDMS microchannels filled with liquid metal. Using femtosecond laser processing, a crisscross pattern of microchannels is fabricated on a flexible substrate and then filled with liquid metal to create the metamaterial absorber. This method combines precise laser processing, microchannel design, and the tunability of liquid metal, offering significant advantages.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0007] In one embodiment of the present invention, a method for preparing a metamaterial absorber based on PDMS microchannels filled with liquid metal is proposed. The method comprises:

[0008] Using the built femtosecond laser processing system, the PDMS film was placed on a three-axis displacement platform. The Z axis of the three-axis displacement platform was controlled by a computer to focus the femtosecond laser on the surface of the PDMS film. The microchannel with a crisscross unit structure was processed on the surface of the PDMS film through the processing path set in the computer.

[0009] Spin-coat PDMS colloid on the surface of the unprocessed PDMS film and heat it to semi-solidify it;

[0010] Use a semi-cured PDMS film to cover the processed PDMS film surface and heat cure it;

[0011] Liquid metal is injected into the microchannel of the M-shaped unit structure, and the channels at both ends are sealed.

[0012] Furthermore, the femtosecond laser processing system includes: a femtosecond laser, an aperture, a reflector, a beam splitter, an optical isolator, a microscope, a halogen lamp, a CCD camera, a three-dimensional displacement platform and a computer; the femtosecond laser is used to generate a laser pulse of extremely short duration; the beam splitter is used to divide the laser beam into two parts, one part is used for processing, and the other part is used for monitoring or auxiliary processing; the microscope is used to observe and monitor the surface state of the PDMS film during the processing process, and observe the effect of femtosecond laser processing and the microstructural changes of the PDMS film through magnification; the computer is used to control and monitor the entire system, including the parameter setting of the laser pulse and the planning of the processing path.

[0013] Furthermore, the M-shaped unit structure has multiple staggered electromagnetic resonance modes, and through geometric arrangement in different directions, the structure produces local resonance in multiple frequency ranges, thereby achieving broadband absorption.

[0014] Furthermore, the M-shaped unit structure disperses the propagation path of electromagnetic waves through its symmetry and cross structure, forming multiple absorption channels, further enhancing the overall wave absorption effect.

[0015] Furthermore, when the 'M'-shaped unit structure is processed by femtosecond laser, the size of the 'M'-shaped unit can be set to achieve the coupling effect of the electric field and the magnetic field, thereby enhancing the absorption of electromagnetic waves in a local area.

[0016] Furthermore, the M-shaped unit structure is adjustable, and by combining it with liquid metal, piezoelectric material or deformable material, dynamic adjustment of the wave absorbing performance can be achieved.

[0017] Furthermore, the liquid metal uniformly fills the crisscross unit structure in a fluid state and deforms freely when subjected to an external force, maintaining an arbitrarily set shape.

[0018] Beneficial effects:

[0019] Liquid metals have attracted widespread attention in the field of flexible electronics due to their low melting point and liquid state at room temperature. Gallium-based alloys, such as gallium-indium alloys, are particularly promising for the development of flexible electronics. Gallium-based alloys, such as gallium-indium alloys, are not only less toxic but also exhibit greater stability in contact with air and water than other metals. This has paved the way for the development of flexible electronics. These materials transcend the limitations of traditional metals, easily filling complex three-dimensional structures in a fluid state and freely deforming and maintaining arbitrary shapes when subjected to external forces. This significantly enhances the feasibility of flexible electronic devices in terms of structural design and functional realization. Furthermore, liquid metals' high electrical conductivity and low volatility make them ideal as electronic conductors. This gives them broad potential for applications in flexible circuits, stretchable conductors, microfluidic systems, biomedical sensors, self-healing circuits, and soft robotics.

[0020] 2. The application of the 'M'-shaped unit structure in metamaterial absorbers significantly enhances absorption through its unique geometric design. This structure features multiple interlaced electromagnetic resonance modes. The geometric arrangement in different directions enables localized resonance across multiple frequency ranges, thus achieving broadband absorption. The 'M'-shaped unit design optimizes impedance matching, reduces reflection loss, and increases absorption, effectively absorbing more electromagnetic waves. Furthermore, the symmetry and cross-section of the 'M'-shaped unit disperse the propagation path of electromagnetic waves, forming multiple absorption channels, further enhancing the overall absorption effect. Furthermore, the 'M'-shaped unit structure can be flexibly adjusted in size during femtosecond laser processing. By adjusting the unit size, the coupling effect of the electric and magnetic fields is achieved, thereby enhancing electromagnetic wave absorption in a localized area. The 'M'-shaped unit structure also offers flexible adjustability. By combining it with liquid metal, piezoelectric materials, or deformable materials, the absorption performance can be dynamically adjusted to meet diverse application requirements. It exhibits significant potential for applications in wearable devices and smart stealth technology. In summary, the M-shaped unit structure greatly improves the absorption performance of the absorber by optimizing electromagnetic resonance, impedance matching and electromagnetic coupling effects, and provides important technical support for the design of broadband absorbers and flexible absorbers. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the femtosecond laser processing system of the present invention;

[0022] In the figure: 1-femtosecond laser, 2-first aperture, 3-second aperture, 4-first reflecting mirror, 5-second reflecting mirror, 6-optical isolator, 7-first beam splitter, 8-third aperture, 9-fourth aperture, 10-electrically controlled switch, 11-third reflecting mirror, 12-fourth reflecting mirror, 13-second beam splitter, 14-microscope, 15-halogen lamp, 16-CCD camera, 17-three-dimensional displacement platform, 18-computer, 19-power supply;

[0023] Figure 2 This is a flow chart of the method for preparing a metamaterial absorber based on PDMS microchannels filled with liquid metal;

[0024] Figure 3 It is a schematic diagram of the M-shaped unit structure on the surface of the PDMS film of the present invention. DETAILED DESCRIPTION

[0025] The principles and spirit of the present invention will be described below with reference to several exemplary embodiments. It should be understood that these embodiments are provided solely to enable those skilled in the art to better understand and design the present invention, and are not intended to limit the scope of the present invention in any way. Rather, these embodiments are provided to make this disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0026] Those skilled in the art will appreciate that embodiments of the present invention may be implemented as a device, apparatus, apparatus, method, or computer program product. Therefore, the present disclosure may be implemented in the following forms: entirely in hardware, entirely in software (including firmware, resident software, microcode, etc.), or in a combination of hardware and software.

[0027] According to an embodiment of the present invention, a method for fabricating a metamaterial absorber based on PDMS microchannels filled with liquid metal is proposed. This metamaterial absorber is fabricated by laser machining microchannels with a 'P'-shaped' structure on a flexible substrate and then filled with liquid metal. This process combines laser precision machining, microchannel design, and the tunability of liquid metal, offering significant advantages. First, laser machining can precisely create the P'-shaped structure on a flexible substrate (such as PDMS). This highly symmetrical and staggered structure can induce resonance effects across multiple frequency bands, optimizing absorption performance. The P'-shaped structure effectively enhances the interaction between electromagnetic waves and the material through staggered electromagnetic resonance modes, thereby achieving broadband absorption. Liquid metal is then injected into these microchannels. The excellent conductivity and low viscosity of the liquid metal ensure uniform distribution within the microchannels, achieving effective absorption. This provides an innovative solution for applications in flexible and wearable devices and smart stealth technology.

[0028] The principles and spirit of the present invention are explained in detail below with reference to several representative embodiments of the present invention.

[0029] The overall scheme adopted by the present invention includes two parts: the construction of a femtosecond laser processing system and the preparation method of a metamaterial absorber based on PDMS microchannels filled with liquid metal.

[0030] 1. Construction of femtosecond laser direct processing system

[0031] like Figure 1 As shown, the femtosecond laser processing system includes: a femtosecond laser 1, a first aperture 2, a second aperture 3, a first reflector 4, a second reflector 5, an optical isolator 6, a first beam splitter 7, a third aperture 8, a fourth aperture 9, an electric switch 10, a third reflector 11, a fourth reflector 12, a second beam splitter 13, a microscope 14, a halogen lamp 15, a CCD camera 16, a three-dimensional displacement platform 17, a computer 18, and a power supply 19. Components 1-14 constitute the femtosecond laser processing optical path, which is used to determine the position of the femtosecond laser optical path.

[0032] Femtosecond lasers: Femtosecond lasers generate extremely short laser pulses. These ultrashort pulses have extremely high peak power and can concentrate energy on the material surface in a very short time, enabling precise material removal or modification.

[0033] First aperture 2, second aperture 3, third aperture 8, and fourth aperture 9: Apertures are used to limit the diameter of the laser beam, remove stray light at the beam edge, and improve beam quality and stability. An aperture is typically a metal plate with a small hole. Only the beam that passes through the hole can continue to propagate.

[0034] First reflector 4, second reflector 5, third reflector 11, and fourth reflector 12: Mirrors are used to change the propagation direction of the laser beam, allowing the laser to be transmitted along a predetermined path to the processing area. Mirrors typically have high reflectivity to reduce laser energy loss.

[0035] First beam splitter 7, second beam splitter 13: Beam splitters are used to split the laser beam into two parts: one for processing and the other for monitoring or auxiliary processing. Beam splitters typically have a certain transmittance and reflectivity, and the energy ratio of the two beams can be adjusted as needed.

[0036] Optical isolator 6: The optical isolator ensures the unidirectional transmission of the laser beam, preventing the reflected light from returning to the laser, thereby protecting the laser from damage and ensuring the stable operation of the system.

[0037] Microscope (10x) 14: The microscope is used to observe and monitor the surface state of the sample during the processing process, and to observe the effect of laser processing and the microstructural changes of the sample through magnification.

[0038] 3D displacement platform 17: The 3D displacement platform is used to fix and move the sample for processing. Through precise displacement control, different parts of the sample are processed by laser in sequence. The sample is the material to be processed (PDMS film).

[0039] Calculator 18: The computer controls and monitors the entire system through control software, including setting laser pulse parameters and planning processing paths. The control unit is responsible for converting computer instructions into specific control signals to drive the various components to work together.

[0040] 2. Preparation method of metamaterial absorber based on PDMS microchannel filled with liquid metal

[0041] like Figure 2 As shown, the processing steps are:

[0042] Step 1: Use the established femtosecond laser processing system to place the PDMS film on the three-axis displacement platform 17, and use the computer 18 to control the Z axis of the three-axis displacement platform 17 so that the femtosecond laser is concentrated on the surface of the PDMS film. The microchannel with a M-shaped unit structure is processed on the surface of the PDMS film through the processing path set in the computer 17.

[0043] PDMS film preparation: Mix PDMS prepolymer and curing agent (such as Sylgard 184) in a ratio of 10:1; stir the PDMS prepolymer and curing agent thoroughly; pour the mixture into a mold and remove bubbles (using a vacuum degassing machine); cure at room temperature or under heating conditions, for example, at 60°C for 2 hours.

[0044] The femtosecond laser parameters were set by computer 17, with power of 120M, scanning speed of 10mm / s, and repetition frequency of 20kHz. A microchannel with a crisscross unit structure was machined on the surface of the PDMS film, as shown in FIG. Figure 3 shown.

[0045] The M-shaped unit structure has multiple staggered electromagnetic resonance modes. Through geometric arrangement in different directions, the structure produces local resonance in multiple frequency ranges, thereby achieving broadband absorption.

[0046] The M-shaped unit structure disperses the propagation path of electromagnetic waves through its symmetry and cross structure, forming multiple absorption channels and further enhancing the overall wave absorption effect.

[0047] When the M-shaped unit structure is processed by femtosecond laser, the size of the M-shaped unit can be set to achieve the coupling effect of the electric field and the magnetic field, thereby enhancing the absorption of electromagnetic waves in the local area.

[0048] The M-shaped unit structure is adjustable and can achieve dynamic adjustment of the wave absorbing performance by combining it with liquid metal, piezoelectric material or deformable material.

[0049] Step 2: Spin-coat PDMS colloid on the surface of the unprocessed PDMS film.

[0050] Preparation of PDMS colloid: Mix the PDMS prepolymer and solvent evenly to form a colloid of a certain viscosity. The ratio of solvent can be adjusted as needed to obtain the desired colloid viscosity.

[0051] Set the spin coating speed to 800 rpm and the spin coating time to 30 seconds on the spin coater. By adjusting the spin coating speed and time, the thickness of the spin coating layer can be controlled to 100 μm.

[0052] Step 3: Heat the spin-coated PDMS film to make it semi-cured, so that the solvent in the spin-coated layer evaporates and the PDMS molecules begin to cross-link to form a semi-cured PDMS film.

[0053] Step 4: Cover the processed PDMS film with a semi-cured PDMS film. Heat at 70°C for 6 hours to firmly bond the two PDMS films together to form a single structure.

[0054] Step 5: Inject liquid metal into the microchannel of the M-shaped unit structure and seal the channels at both ends to ensure that the liquid metal does not leak.

[0055] The liquid metal evenly fills the M-shaped unit structure in a fluid state and deforms freely when subjected to external force, maintaining an arbitrarily set shape.

[0056] It should be noted that although the operations of the method of the present invention are described in a specific order in the above embodiments and drawings, this does not require or imply that these operations must be performed in this specific order, or that all illustrated operations must be performed to achieve the desired results. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

[0057] The method for preparing a metamaterial absorber based on PDMS microchannels filled with liquid metal proposed in the present invention has the following advantages:

[0058] Liquid metals have attracted widespread attention in the field of flexible electronics due to their low melting point and liquid state at room temperature. Gallium-based alloys, such as gallium-indium alloys, are particularly promising for the development of flexible electronics. Gallium-based alloys, such as gallium-indium alloys, are not only less toxic but also exhibit greater stability in contact with air and water than other metals. This has paved the way for the development of flexible electronics. These materials transcend the limitations of traditional metals, allowing them to easily fill complex three-dimensional structures while in a fluid state. They can also deform freely under external forces, maintaining arbitrary shapes. This significantly enhances the feasibility of flexible electronic devices in terms of structural design and functional realization. Furthermore, liquid metals' high electrical conductivity and low volatility make them ideally suited for use as electronic conductors. This holds great potential for applications in flexible circuits, stretchable conductors, microfluidic systems, biomedical sensors, self-healing circuits, and soft robotics.

[0059] 2. The application of the 'M'-shaped unit structure in metamaterial absorbers significantly enhances absorption through its unique geometric design. This structure features multiple interlaced electromagnetic resonance modes. The geometric arrangement in different directions enables localized resonance across multiple frequency ranges, thus achieving broadband absorption. The 'M'-shaped unit design optimizes impedance matching, reduces reflection loss, and increases absorption, effectively absorbing more electromagnetic waves. Furthermore, the symmetry and cross-section of the 'M'-shaped unit disperse the propagation path of electromagnetic waves, forming multiple absorption channels, further enhancing the overall absorption effect. Furthermore, femtosecond laser processing of this structure allows for flexible adjustment of the 'M'-shaped unit size. By adjusting the unit size, the coupling effect of the electric and magnetic fields is achieved, thereby enhancing electromagnetic wave absorption in a localized area. The 'M'-shaped unit design also offers flexible adjustability. By combining it with liquid metal, piezoelectric materials, or deformable materials, the absorption performance can be dynamically adjusted to meet diverse application requirements. It exhibits significant potential in areas such as wearable devices and intelligent stealth technology. In summary, the M-shaped unit structure greatly improves the absorption performance of the absorber by optimizing electromagnetic resonance, impedance matching and electromagnetic coupling effects, and provides important technical support for the design of broadband absorbers and flexible absorbers.

[0060] Although the spirit and principles of the present invention have been described with reference to several specific embodiments, it should be understood that the present invention is not limited to the specific embodiments disclosed, and the division into various aspects does not mean that the features of these aspects cannot be combined to benefit. Such division is only for the convenience of expression. The present invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0061] Regarding the limitation of the protection scope of the present invention, those skilled in the art should understand that, based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the protection scope of the present invention.

Claims

1. A method for preparing a metamaterial absorber based on PDMS microchannels filled with liquid metal, characterized in that: The preparation method comprises: Using the built femtosecond laser processing system, the PDMS film was placed on a three-axis displacement platform. The Z axis of the three-axis displacement platform was controlled by a computer to focus the femtosecond laser on the surface of the PDMS film. The microchannel with a crisscross unit structure was processed on the surface of the PDMS film through the processing path set in the computer. Spin-coat PDMS colloid on the surface of the unprocessed PDMS film and heat it to semi-solidify it; Use a semi-cured PDMS film to cover the processed PDMS film surface and heat cure it; Liquid metal is injected into the microchannel of the M-shaped unit structure, and the channels at both ends are sealed.

2. The method for preparing a metamaterial absorber based on PDMS microchannels filled with liquid metal according to claim 1, characterized in that: The femtosecond laser processing system includes: a femtosecond laser, an aperture, a reflector, a beam splitter, an optical isolator, a microscope, a halogen lamp, a CCD camera, a three-dimensional displacement platform and a computer. The femtosecond laser is used to generate extremely short-duration laser pulses; the beam splitter is used to split the laser beam into two parts, one for processing and the other for monitoring or auxiliary processing; the microscope is used to observe and monitor the surface state of the PDMS film during the processing process, and observe the effect of femtosecond laser processing and the microstructural changes of the PDMS film through magnification; the computer is used to control and monitor the entire system, including setting the parameters of the laser pulse and planning the processing path.

3. The method for preparing a metamaterial absorber based on PDMS microchannels filled with liquid metal according to claim 1, characterized in that: The 'M'-shaped unit structure has multiple staggered electromagnetic resonance modes. Through geometric arrangement in different directions, the structure generates local resonance in multiple frequency ranges, thereby achieving broadband absorption.

4. The method for preparing a metamaterial absorber based on PDMS microchannels filled with liquid metal according to claim 3, characterized in that: The M-shaped unit structure disperses the propagation path of electromagnetic waves through its symmetry and cross structure, forming multiple absorption channels, thereby further enhancing the overall wave absorption effect.

5. The method for preparing a metamaterial absorber based on PDMS microchannels filled with liquid metal according to claim 1, characterized in that: When the M-shaped unit structure is processed by femtosecond laser, the size of the M-shaped unit can be set to achieve the coupling effect of the electric field and the magnetic field, thereby enhancing the absorption of electromagnetic waves in the local area.

6. The method for preparing a metamaterial absorber based on PDMS microchannels filled with liquid metal according to claim 1, characterized in that: The crisscross unit structure is adjustable and can achieve dynamic adjustment of the wave absorbing performance by combining it with liquid metal, piezoelectric material or deformable material.

7. The method for preparing a metamaterial absorber based on PDMS microchannels filled with liquid metal according to claim 1, characterized in that: The liquid metal uniformly fills the crisscross unit structure in a fluid state, and deforms freely when subjected to an external force, maintaining an arbitrarily set shape.

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