A liquid metal reconstructed super surface and its manufacturing method

Abstract

The present invention discloses a liquid metal reconfigurable metasurface and a manufacturing method thereof. The liquid metal reconfigurable metasurface includes a sealing layer, a flexible dielectric layer, a driving and control layer, and an electromagnetic reflection layer. The sealing layer, the flexible dielectric layer, the driving and control layer, and the electromagnetic reflection layer are stacked in sequence. A plurality of microchannel structures are arranged in an array on the flexible dielectric layer. The microchannel structures have flow channels for liquid metal to flow. The electromagnetic reflection layer is used for reflecting electromagnetic waves, and the driving and control layer is used for controlling the flow position and shape of the liquid metal in the flow channels; wherein, the shape of the flow channel of each microchannel structure is a shape similar to a Chinese character '田' (field). Through the reversible continuous flow control of liquid metal in the microchannel structures with a shape similar to a Chinese character '田' (field), the present invention realizes the continuous dynamic reconfiguration of electromagnetic response frequency, achieves polarization conversion with S, C, and X broadband response capabilities, the continuous reconfiguration bandwidth is greater than 7 GHz, and has polarization insensitivity, incident angle insensitivity, and flexibility capabilities.

Description

Technical Field

[0001] The present invention relates to the technical field of artificial electromagnetic materials, and in particular to a liquid metal reconstructed supersurface and a manufacturing method thereof. Background Art

[0002] Metasurfaces, as a new type of artificial composite microstructure, possess extraordinary physical properties not found in natural materials. Due to the designability of their structural properties, they can flexibly manipulate material properties and electromagnetic wave responses through appropriate structural design, leading to rapid development and application in camouflage and stealth technology, communications technology, and sensing technology.

[0003] With the advancement of high-precision micro-nano fabrication processes, micro-nanoscale structures can be precisely fabricated, expanding their application areas and scope. While metasurfaces offer exceptional performance, their material properties and response to electromagnetic waves are fixed after design and fabrication. These properties cannot adapt to environmental changes, effectively preventing them from achieving dynamic performance. Therefore, leveraging the exceptional performance of metasurfaces while also achieving tunability in their structural properties and electromagnetic response is crucial for further expanding and enhancing their performance and application. Recent research has explored techniques such as conductive polymers, liquid crystals, MEMS electrostatic structures, and diodes to actively modify metasurface structural characteristics and achieve tunable electromagnetic response. However, the tunable range of conductivity and dielectric constant of conductive polymers remains limited, and stability is difficult to ensure. Liquid crystal molecules, which adjust electromagnetic parameters based on their orientation under varying electric fields, suffer from narrow tuning bandwidths and long response times. MEMS electrostatic structures struggle to meet broadband requirements, and large-scale applications pose structural reliability challenges. Furthermore, diodes have limited tuning states, significant nonlinear effects, and insufficient broadband tuning capabilities. Therefore, although conventional metasurface arrays can achieve dynamic control of electromagnetic wave responses, they still face problems such as limited control states, insufficient continuous adjustment capabilities, and the need to improve flexibility. In particular, the above method can usually only achieve adjustment between two states for the same unit. The adjustment of any electromagnetic wave response requires a large number of unit encodings. Combined with the application requirements of metasurfaces, it is also necessary to further realize the multi-state continuous adjustment capability of metasurface units within a broadband adjustment range.

[0004] As a metal that can flow continuously at room temperature, liquid metal combines the excellent properties of traditional rigid and flexible materials and has the following characteristics: 1) a very low melting point, being liquid at room temperature; 2) low viscosity, facilitating injection into microchannels; 3) relatively high electrical conductivity, although lower than that of copper but far higher than other conductive liquids; 4) not easily evaporating and having stable performance. Utilizing the arbitrary fluidity of liquid metal, especially microfluidizing liquid metal and combining it with the channel structure, flow control can be achieved in the metasurface unit structure, and it can be applied to the reconstruction of metasurface structure parameters and structure forms, having the ability to regulate conventional metasurfaces. However, the application of existing liquid metals in microchannel structures is still in its infancy, and there are few reports on the influence of the shape of liquid metal in microchannel structures on metasurface performance. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a liquid metal reconfigurable metasurface that can dynamically and flexibly adjust the performance of the metasurface in multiple states and its manufacturing method.

[0006] To achieve the above purpose, in the first aspect of the present invention, a liquid metal reconfigurable metasurface is provided, including a sealing layer, a flexible dielectric layer, a drive control layer, and an electromagnetic reflection layer. The sealing layer, the flexible dielectric layer, the drive control layer, and the electromagnetic reflection layer are stacked in sequence. A plurality of microchannel structures are arranged in an array on the flexible dielectric layer. The microchannel structures have flow channels for liquid metal to flow. The electromagnetic reflection layer is used for reflecting electromagnetic waves, and the drive control layer is used to control the flow position and shape of liquid metal in the flow channels. Among them, the shape of the flow channel of each microchannel structure is similar to a "field" shape.

[0007] Furthermore, the flow channel includes an outer peripheral circular flow channel, a horizontal flow channel, and a vertical flow channel. The horizontal flow channel and the vertical flow channel intersect and are connected. The horizontal flow channel and the vertical flow channel are respectively arranged radially along the outer peripheral circular flow channel and are connected to it.

[0008] Furthermore, the drive control layer controls the shape of the liquid metal in the flow channel to be symmetric about the center line of the vertical flow channel left and right, and controls the shape of the liquid metal in the flow channel to be symmetric about the center line of the horizontal flow channel up and down.

[0009] Furthermore, the outer peripheral circular flow channel is divided into a first arc segment, a second arc segment, a third arc segment, and a fourth arc segment by the intersection points of the horizontal flow channel and the vertical flow channel with the outer peripheral circular flow channel. The drive control layer controls the liquid metal in the horizontal flow channel and the vertical flow channel to be continuous, and controls the liquid metal in the first arc segment, the second arc segment, the third arc segment, and the fourth arc segment in the outer peripheral circular flow channel to be discontinuous.

[0010] Further, the gap adjustment range S of the discontinuous liquid metal in the first arc segment, the second arc segment, the third arc segment and the fourth arc segment is 0 < S < 2 mm, 2 < S < 7.5 mm or S > 7.5 mm.

[0011] Further, the sealing layer is fixed on the flexible dielectric layer by bonding to encapsulate the liquid metal in the microchannel structure.

[0012] Further, the material of the flexible dielectric layer is PDMS, PMMA or PET.

[0013] Further, the driving and control layer controls the flow of the liquid metal in the microchannel structure, and the control methods include electromagnetic, voltage and / or pressure.

[0014] Further, a conductive liquid is preset in the flow channel of the microchannel structure.

[0015] Further, the driving and control layer includes a first electrode and a second electrode. The first electrode and the second electrode are electrically connected to the liquid metal in the flow channel of the microchannel structure through the conductive liquid, and the flow position and shape of the liquid metal in the flow channel of the microchannel structure are dynamically adjusted according to the voltage magnitudes applied on the first electrode and the second electrode.

[0016] Further, the conductive liquid is an acidic or alkaline solution, and the conductive liquid is injected into the flow channel of the microchannel structure before the liquid metal.

[0017] Further, the first electrode and the second electrode are formed in the driving and control layer. Through holes communicating with the flow channel are provided in the flexible dielectric layer, and the leads of the first electrode and the second electrode pass through the through holes to be electrically connected to the liquid metal.

[0018] Further, the material of the electromagnetic reflection layer is metal.

[0019] Further, the continuous reconstruction bandwidth of the liquid metal reconfigurable metasurface is greater than 7 GHz.

[0020] In the second aspect of the present invention, a manufacturing method of a liquid metal reconfigurable metasurface is provided, including the following steps:

[0021] 1) Form an array formed by a plurality of microchannel structures on a flexible dielectric layer; wherein, the microchannel structure has a flow channel for the liquid metal to flow, and the shape of the flow channel is similar to a "field" character;

[0022] 2) Inject liquid metal into the flow channel of each microchannel structure respectively;

[0023] 3) Package a sealing layer on the flexible dielectric layer;

[0024] 4) Form a driving control layer under the flexible dielectric layer;

[0025] 5) Set an electromagnetic reflection layer under the driving control layer.

[0026] The liquid metal reconfigurable metasurface of the present invention forms a "field" - shaped micro - channel structure in the flexible dielectric layer. Through the reversible continuous flow control of liquid metal in the "field" - shaped micro - channel structure, it realizes the continuous dynamic reconfiguration of the electromagnetic response frequency, achieves polarization conversion with S, C, X broadband response capabilities, the continuous reconfiguration bandwidth is greater than 7 GHz, and has polarization insensitivity, incident angle insensitivity, and flexibility capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0028] Figure 1-Figure 3 It is a schematic structural diagram of the liquid metal reconfigurable metasurface according to an embodiment of the present invention;

[0029] Figure 4 It is an electromagnetic response diagram of the liquid metal reconfigurable metasurface according to an embodiment of the present invention;

[0030] Figure 5 It is a flowchart of the manufacturing method of the liquid metal reconfigurable metasurface according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will further describe the embodiments of the present invention in detail with reference to the drawings.

[0032] As Figure 1-Figure 3As shown in the figure, the liquid metal reconfigurable metasurface of the present invention includes a sealing layer 1, a flexible dielectric layer 2, a driving control layer 3, and an electromagnetic reflection layer 4. The sealing layer 1, the flexible dielectric layer 2, the driving control layer 3, and the electromagnetic reflection layer 4 are stacked in sequence. A plurality of microchannel structures 21 are arranged in an array on the flexible dielectric layer 2. A flow channel for the liquid metal 5 to flow is provided in the microchannel structure 21. The electromagnetic reflection layer 4 is used for reflecting electromagnetic waves. The driving control layer 3 is used to control the flow position and shape of the liquid metal 5 in the flow channel. Among them, the shape of the flow channel of each microchannel structure 21 is a shape similar to a "field" character. The flow channel includes an outer peripheral circular flow channel 22, a horizontal flow channel 23, and a vertical flow channel 24. The horizontal flow channel 23 and the vertical flow channel 24 intersect and communicate with each other. The horizontal flow channel 23 and the vertical flow channel 24 are respectively arranged radially along the outer peripheral circular flow channel 22 and communicate with it. Among them, the driving control layer 3 controls the shape of the liquid metal in the flow channel to be symmetric about the center line of the vertical flow channel left and right, and controls the shape of the liquid metal in the flow channel to be symmetric about the center line of the horizontal flow channel up and down. Specifically, the outer peripheral circular flow channel 22 is divided into a first arc segment 221, a second arc segment 222, a third arc segment 223, and a fourth arc segment 224 by the intersection points of the horizontal flow channel 23 and the vertical flow channel 24 with the outer peripheral circular flow channel 22. The driving control layer 3 controls the liquid metal in the horizontal flow channel 23 and the vertical flow channel 24 to be continuous, and controls the liquid metal in the first arc segment 221, the second arc segment 222, the third arc segment 223, and the fourth arc segment 224 in the outer peripheral circular flow channel 22 to be discontinuous.

[0033] Under the driving effects of pressure, voltage, electromagnetic field, etc. of the driving control layer 3, the liquid metal 4 realizes continuous flow in the flow channel of the microchannel structure 21, and changes at different flow positions and shapes in the flow channel of the microchannel structure 21, thereby reconfiguring the structure of the microchannel structure and the liquid metal therein. Each change in the flow position and shape of the liquid metal in the microchannel structure corresponds to a working state of the metasurface, so as to realize the dynamic adjustment of the performance of the metasurface in multiple states. Since the shape of the flow channel of the microchannel structure is a shape similar to a "field" character, continuous dynamic reconstruction of the electromagnetic response frequency is achieved by controlling the continuous flow of the liquid metal, realizing the S, C, X broadband response capabilities, the reconstruction bandwidth is greater than 7 GHz, and it has polarization insensitivity, incident angle insensitivity, and flexibility capabilities.

[0034] As <C Figure 1 and 2As shown, by adjusting the continuity of the liquid metal in the horizontal flow channel 23 and the vertical flow channel 24, the adjustment range S of the gaps of the discontinuous liquid metal in the first arc segment 221, the second arc segment 222, the third arc segment 223 and the fourth arc segment 224 is 0 < S < 2 mm, 2 < S < 7.5 mm or S > 7.5 mm. By continuously adjusting the electrical length over a long distance through the continuous flow of the liquid metal, broadband adjustment of electromagnetic response is achieved. Under an external force, the liquid metal flows continuously and with high precision in the flow channel, and the precision is achieved at 1‰. Figure 1 , Figure 2 The smaller the gaps of the discontinuous liquid metal in the first arc segment, the second arc segment, the third arc segment and the fourth arc segment in Figure 1 and Figure 2 , the lower the frequency. As the liquid metal flows, the spacing becomes larger and the response frequency becomes higher. Specifically, when the adjustment range of the gaps of the discontinuous liquid metal in the first arc segment, the second arc segment, the third arc segment and the fourth arc segment is 0 < S < 2 mm, the response frequency is in the S band; when the adjustment range of the gaps of the discontinuous liquid metal in the first arc segment, the second arc segment, the third arc segment and the fourth arc segment is 2 < S < 7.5 mm, the response frequency is in the C band; when the adjustment range of the gaps of the discontinuous liquid metal in the first arc segment, the second arc segment, the third arc segment and the fourth arc segment is S > 7.5 mm, the response frequency is in the X band.

[0035] Optionally, the sealing layer 1 is fixed on the flexible dielectric layer 2 by bonding to encapsulate the liquid metal 5 in the microchannel structure 21, avoiding problems such as leakage of the liquid metal.

[0036] Optionally, the microchannel structure 21 is fabricated on the flexible dielectric layer 2 of the metasurface. For the electromagnetic wave response characteristics, according to the conventional metasurface configuration, parameters such as the microchannel structure 21 and its width and height are designed. The flow channels of the microchannel structure 21 are realized by micro-nano processing techniques, including photolithography, nanoimprinting and other process methods. The structure of the microchannel structure 21 can be an array composed of "field" shapes of the same size, or an array composed of "field" shapes of different sizes.

[0037] Optionally, the material of the flexible dielectric layer 2 is PDMS, PMMA or PET.

[0038] Optionally, the driving and control layer 3 controls the flow of the liquid metal 5 in the microchannel structure 21, and the control methods include electromagnetic, voltage and / or pressure. Under the control of the control algorithm and the driving and control circuit, the liquid metal 4 can flow continuously in the flow channel, and the flow and fixed position are controllable. Different flow positions represent different working states, and each microchannel structure 21 realizes multiple different working states under the action of the liquid metal flow reconstruction. The metasurface units in different liquid metal flow states are jointly encoded to achieve the regulation of the electromagnetic wave response.

[0039] Optionally, a conductive liquid is pre - placed in the flow channels of the micro - channel structure 21. The control circuit of the driving and control layer 3 is integrated on the lower side of the micro - channel structure 21. Each driving and control layer 3 includes a first electrode 31 and a second electrode 32. The first electrode 31 and the second electrode 32 are embedded in the control - circuit structure layer of the driving and control layer 3. The first electrode 31 and the second electrode 32 are electrically connected to the liquid metal 4 in the flow channels of the micro - channel structure 21 through the conductive liquid. The flow position and shape of the liquid metal 4 in the flow channels of the micro - channel structure 21 are dynamically adjusted according to the magnitudes of the voltages applied on the first electrode 31 and the second electrode 32.

[0040] Optionally, the conductive liquid injected into the micro - channel structure 21 is an acidic or alkaline solution, and the conductive liquid is injected into the flow channels of the micro - channel structure 21 before the liquid metal 4. In this way, the oxide layer on the surface of the subsequently injected liquid metal can be removed, improving the fluidity of the liquid metal in the micro - flow unit.

[0041] Optionally, the electromagnetic reflection layer 4 can be a metal backplane. The electromagnetic wave is reflected by the metal backplane to increase the attenuation of the electromagnetic wave. The metal backplane can be made of materials such as aluminum film. The electromagnetic response of the liquid - metal reconfigurable metasurface is as Figure 4 shown. By reconfiguring the structural morphology of the metasurface through the flow of liquid metal, the dynamic reconfiguration of the electromagnetic response is realized. It has the function of continuously adjusting the electromagnetic frequency above 7 GHz, and is insensitive to polarization, incident angle, and has flexibility.

[0042] Optionally, the continuous reconfiguration bandwidth of the liquid - metal reconfigurable metasurface is greater than 7 GHz.

[0043] As Figure 5 shown, the manufacturing method of the liquid - metal reconfigurable metasurface includes the following steps:

[0044] Step S51: Form an array formed by multiple micro - channel structures on the flexible dielectric layer; wherein, the micro - channel structure has a flow channel for liquid - metal flow, and the shape of the flow channel is similar to a "field" character.

[0045] Step S52: Inject liquid metal into the flow channels of each micro - channel structure respectively.

[0046] Step S53: Package a sealing layer on the flexible dielectric layer.

[0047] Step S54: Form a driving and control layer under the flexible dielectric layer.

[0048] Step S55: Set an electromagnetic reflection layer under the driving and control layer.

[0049] The present invention uses a liquid metal and a microchannel structure array in the shape of a "field" character to replace the fixed metal array of the conventional metasurface structure. By controlling the continuous flow of the liquid metal in the metasurface array unit, a multi-bit working state (theoretically an infinite number of working states) is achieved for the same unit. Encoding between multiple dynamically reconfigurable units enables dynamic reconfiguration of the metasurface structure properties and flexible regulation of the electromagnetic wave response, solving the problems faced by conventional metasurface reconstruction methods, such as limited regulation states, insufficient continuous adjustment ability, and the need to improve flexibility. Fundamentally improving the performance of conventional metasurfaces, further expanding their application scope, and realizing capabilities such as intelligent electromagnetic camouflage stealth and dynamically reconfigurable communication. The present invention can be applied to metasurfaces in bands such as microwave and terahertz, and can be applied to fields such as dynamic camouflage stealth and reconfigurable communication. <> <>

[0050] The terms "first" and "second" are used for descriptive purposes only and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined by "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "multiple" is two or more. <> <>

[0051] Those of ordinary skill in the art can understand that all or part of the steps to implement the above embodiments can be completed by hardware, or can be completed by a program instructing relevant hardware. The program can be stored in a computer-readable storage medium, and the above-mentioned storage medium can be a read-only memory, a magnetic disk, an optical disk, etc. <> <>

[0052] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. Liquid metal reconstructed metasurface, characterized by: It includes a sealing layer, a flexible dielectric layer, a drive control layer and an electromagnetic reflection layer. The sealing layer, the flexible dielectric layer, the drive control layer and the electromagnetic reflection layer are stacked in sequence. A plurality of microchannel structures are arranged in an array on the flexible dielectric layer. A flow channel for liquid metal to flow is provided in the microchannel structure. The electromagnetic reflection layer is used for reflecting electromagnetic waves. The drive control layer is used to control the flow position and shape of the liquid metal in the flow channel. Among them, the shape of the flow channel of each microchannel structure is similar to the Chinese character "field". The flow channel includes an outer peripheral circular flow channel, a horizontal flow channel and a vertical flow channel. The horizontal flow channel and the vertical flow channel intersect and communicate with each other. The horizontal flow channel and the vertical flow channel are respectively arranged radially along the outer peripheral circular flow channel and communicate with it. The drive control layer controls the shape of the liquid metal in the flow channel to be symmetric about the center line of the vertical flow channel and controls the shape of the liquid metal in the flow channel to be symmetric about the center line of the horizontal flow channel. The outer peripheral circular flow channel is divided into a first arc segment, a second arc segment, a third arc segment and a fourth arc segment through the intersection points of the horizontal flow channel and the vertical flow channel with the outer peripheral circular flow channel. The drive control layer controls the liquid metal in the horizontal flow channel and the vertical flow channel to be continuous and controls the liquid metal in the first arc segment, the second arc segment, the third arc segment and the fourth arc segment in the outer peripheral circular flow channel to be discontinuous. The gap adjustment range S of the discontinuous liquid metal in the first arc segment, the second arc segment, the third arc segment and the fourth arc segment is S > 7.5 mm.

2. The liquid metal reconstructed metasurface according to claim 1, wherein: The drive control layer controls the flow control mode of the liquid metal in the microchannel structure including electromagnetic, voltage and / or pressure.

3. The liquid metal reconstructed metasurface according to claim 2, wherein: The drive control layer includes a first electrode and a second electrode. The first electrode and the second electrode are electrically connected to the liquid metal in the flow channel of the microchannel structure through a conductive liquid. The flow position and shape of the liquid metal in the flow channel of the microchannel structure are dynamically adjusted according to the magnitudes of the voltages applied on the first electrode and the second electrode.

4. The liquid metal reconstructed metasurface according to claim 3, wherein: The first electrode and the second electrode are formed in the drive control layer. Through holes communicating with the flow channel are provided in the flexible dielectric layer. Leads of the first electrode and the second electrode pass through the through holes and are electrically connected to the liquid metal.

5. The liquid metal reconstructed metasurface according to claim 1, wherein: The material of the electromagnetic reflection layer is metal.

6. A method for manufacturing a liquid metal reconstructed metasurface according to any one of claims 1 to 5, characterized in that: It includes the following steps: 1) Form an array formed by a plurality of microchannel structures on the flexible dielectric layer. Among them, a flow channel for liquid metal to flow is provided in the microchannel structure. The shape of the flow channel is similar to the Chinese character "field". 2) Inject liquid metal into the flow channel of each microchannel structure respectively. 3) Package a sealing layer on the flexible dielectric layer. 4) Form a drive control layer under the flexible dielectric layer. 5) Set an electromagnetic reflection layer under the drive control layer.

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