Reconfigurable metasurface based on electrowetting and control method thereof

Abstract

The application relates to the technical field of artificial electromagnetic materials, in particular to a reconfigurable metasurface based on electro-wetting and a control method thereof. The reconfigurable metasurface based on electro-wetting is sequentially provided with a first base layer, a fluid medium layer and a second base layer along a preset direction, the fluid medium layer is provided with metal wires, the fluid medium layer is used for containing conductive liquid, the first base layer is provided with a fixing groove used for fixing the conductive liquid, the second base layer is provided with a driving electrode used for driving the conductive liquid to be connected with part of the metal wires. The reconfigurable metasurface based on electro-wetting can realize the connection between the conductive liquid and different metal wires according to the position difference of the driving electrode of the applied voltage, so that the corresponding mode of the metasurface configuration can be switched, and the geometric size of the metasurface configuration can be changed. The reconfigurable metasurface is easy to realize batch processing, the control mode is simple, the response speed is fast, and rapid metasurface configuration reconfiguration can be realized.

Description

Technical Field

[0001] This invention relates to the field of artificial electromagnetic materials technology, and in particular to a reconfigurable metasurface based on electrowetting and its control method. Background Technology

[0002] A metasurface is an artificially layered material with a thickness less than the corresponding wavelength of an electromagnetic wave, typically composed of periodic metal-dielectric structures. Metasurfaces allow for flexible and effective control over the polarization, amplitude, phase, polarization, and propagation mode of electromagnetic waves. However, the configuration of metasurfaces is currently usually fixed, meaning a fixed electromagnetic wave response. Therefore, to achieve variations in the electromagnetic wave response, the configuration of the metasurface needs to be reconfigurable.

[0003] Currently, reconfigurable metasurfaces can be achieved primarily by adjusting the geometric dimensions of the metal / dielectric structure, or by adjusting parameters such as the conductivity of the metal or the dielectric constant and loss tangent of the dielectric structure. Typical methods of altering the geometric configuration include controlling the electrical connections of the metal structure by switching diodes on and off, regulating the movement of the metal / dielectric structure using MEMS technology, and changing the configuration by pressure-driven liquid metal. Methods of altering the physical properties of the metal / dielectric structure typically involve inducing phase transitions or reactions through optical, thermal, or chemical means to achieve property changes.

[0004] However, a common problem with the aforementioned technologies is that their reconfigurability is achieved within a fixed geometric configuration or a limited range of physical property parameters. This means that as the structure is reconfigured or the physical properties change, the electromagnetic wave response mode is limited. For example, it can only adjust the electromagnetic wave absorption rate, shift the electromagnetic wave absorption peak, switch polarization, adjust the phase, and so on. These technologies cannot change the electromagnetic wave response mode according to needs, such as switching from absorption to polarization conversion or other response modes, which limits the further development of reconfigurable metasurfaces. Summary of the Invention

[0005] The objective of this invention is to at least address the problem of a single response mode in reconfigurable metasurfaces. This objective is achieved through the following technical solution:

[0006] The first aspect of the present invention proposes a reconfigurable metasurface based on electrowetting, wherein the reconfigurable metasurface based on electrowetting is provided with a first base layer, a fluid medium layer and a second base layer sequentially along a predetermined direction;

[0007] A metal wire is disposed within the fluid medium layer, and the fluid medium layer is used to contain the conductive liquid.

[0008] The first base layer is provided with a fixing groove, which is used to fix the conductive liquid;

[0009] A driving electrode is provided in the second base layer, and the driving electrode is used to drive the conductive liquid to connect with part of the metal wire.

[0010] According to the reconfigurable metasurface based on electrowetting of the present invention, the connection between the conductive liquid and different metal wires can be realized according to the different positions of the driving electrode with applied voltage. This allows for switching the corresponding mode of the metasurface configuration and changing the geometric dimensions of the metasurface configuration. The reconfigurable metasurface of the present invention is easy to mass-produce, has a simple control mode, and a fast response speed, enabling rapid metasurface configuration reconstruction.

[0011] In addition, the reconfigurable metasurface based on electrowetting according to the present invention may also have the following additional technical features:

[0012] In some embodiments of the present invention, the first base layer is provided with a top substrate, an electrode layer, a first dielectric layer and a first hydrophobic layer in sequence along a preset direction;

[0013] The second base layer is provided with a second hydrophobic layer, a second dielectric layer and a substrate layer in sequence along a preset direction, and the driving electrodes are arranged on the side of the substrate layer close to the second dielectric layer.

[0014] In some embodiments of the present invention, the arrangement of the plurality of said metal wires forms a square, an equilateral triangle or a regular hexagon.

[0015] In some embodiments of the present invention, the driving electrode is made of aluminum, copper, platinum, silver or titanium.

[0016] In some embodiments of the present invention, the substrate layer is made of silicon or glass;

[0017] Or / and, the first dielectric layer and the second dielectric layer are made of dichloro-p-xylene dimer or silicon dioxide;

[0018] Or / and, the first hydrophobic layer and the second hydrophobic layer are made of dichloro-p-xylene dimer or polytetrafluoroethylene.

[0019] In some embodiments of the present invention, the electrode layer is made of indium tin oxide thin film;

[0020] Or / and, the material of the top substrate is polymethyl methacrylate, polydimethylsiloxane, polyethylene terephthalate, polycarbonate or glass.

[0021] In some embodiments of the present invention, the first hydrophobic layer and the second hydrophobic layer are prepared by thin film deposition or surface chemical grafting.

[0022] In some embodiments of the present invention, the metal wire is made of copper, platinum or gold;

[0023] Or / and, the fluid medium of the fluid medium layer is silicone oil or fluorinated liquid.

[0024] A second aspect of the present invention provides a control method for an electrowetting-based reconfigurable metasurface, for controlling the aforementioned electrowetting-based reconfigurable metasurface, comprising the following steps:

[0025] Add conductive liquid above the driving electrode;

[0026] The first base layer is encapsulated above the driving electrode along a preset direction;

[0027] Fill the fluid medium layer with a fluid medium so that the conductive liquid is encapsulated in the fluid medium;

[0028] A voltage is applied to the driving electrode, thereby changing the configuration of the metasurface.

[0029] In some embodiments of the present invention, gallium indium tin alloy, mercury, or ionic liquid is selected as the conductive liquid. Attached Figure Description

[0030] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0031] Figure 1 A schematic diagram of the structure of a reconfigurable metasurface based on electrowetting according to an embodiment of the present invention is shown.

[0032] Figure 2 A schematic diagram a of an array layout according to an embodiment of the present invention is shown;

[0033] Figure 3 A schematic diagram b of the array layout according to an embodiment of the present invention is shown;

[0034] Figure 4 A schematic diagram c of an array layout according to an embodiment of the present invention is shown;

[0035] Figure 5 A schematic diagram of the connection scheme between the conductive liquid and the metal wire for a cross-shaped layout according to an embodiment of the present invention is shown.

[0036] Figure 6 An example a of cross-shaped metasurface configuration reconstruction according to an embodiment of the present invention is illustrated schematically;

[0037] Figure 7 An example b of cross-shaped metasurface configuration reconstruction according to an embodiment of the present invention is illustrated schematically;

[0038] Figure 8 An example c of cross-shaped metasurface configuration reconstruction according to an embodiment of the present invention is illustrated schematically;

[0039] Figure 9 This is a flowchart of the control method for reconfigurable metasurfaces based on electrowetting according to the present invention.

[0040] The attached figures are labeled as follows:

[0041] 10 is the first base layer, 11 is the top substrate, 12 is the electrode layer, 13 is the first dielectric layer, 14 is the first hydrophobic layer, and 101 is the fixing groove.

[0042] 20 is the second base layer, 21 is the second hydrophobic layer, 22 is the second dielectric layer, 23 is the driving electrode, and 24 is the substrate layer;

[0043] 30 is the fluid medium layer, 31 is the fluid medium, and 32 is the metal wire;

[0044] 40 is a conductive liquid. Detailed Implementation

[0045] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0046] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0047] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0048] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented as "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0049] like Figures 1 to 8 As shown, according to an embodiment of the present invention, a reconfigurable metasurface based on electrowetting is proposed. The reconfigurable metasurface based on electrowetting is provided with a first base layer 10, a fluid medium layer 30, and a second base layer 20 sequentially arranged along a predetermined direction. The fluid medium layer 30 contains a plurality of metal wires 32 and is used to contain a conductive liquid 40. The first base layer 10 is provided with a fixing groove 101 for fixing the conductive liquid 40. The second base layer 20 contains a driving electrode 23, which is used to electrowet and drive the conductive liquid 40 to connect with a portion of the metal wires 32.

[0050] According to the electrowetting-based reconfigurable metasurface of the present invention, the connection between the conductive liquid 40 and different metal wires 32 can be realized depending on the position of the driving electrode 23 with the applied voltage. On the one hand, it is possible to switch the response mode of the metasurface configuration, i.e., the electromagnetic wave, such as switching the modulation phase, polarization, or amplitude. On the other hand, it is possible to change the geometric dimensions of the current metasurface configuration, i.e., change the phase, polarization, or amplitude under the current electromagnetic wave response mode. The present invention uses electrowetting to reconstruct the metasurface configuration, is compatible with IC / MEMS processes, is easy to mass-produce, has a simple control mode, and a fast liquid response speed, enabling rapid metasurface configuration reconstruction.

[0051] This invention relates to a reconfigurable metasurface based on electrowetting. Electrowetting technology refers to altering the wettability of a droplet on its underlying solid structure (typically a strongly hydrophobic material) by applying a voltage between upper and lower substrates. This alters the contact angle, causing the droplet to deform and shift. Wetting refers to the process by which one fluid replaces another on a solid surface. Wetting occurs when a liquid spreads on a solid surface, and the solid-liquid interface tends to expand, meaning the liquid's adhesion to the solid surface is greater than its cohesive force. Conversely, nonwetting occurs when a liquid cannot spread on a solid surface, and the interface tends to shrink into a spherical shape. Nonwetting means the liquid's adhesion to the solid surface is less than its cohesive force.

[0052] In some embodiments, the first base layer 10 is sequentially provided with a top substrate 11, an electrode layer 12, a first dielectric layer 13, and a first hydrophobic layer 14 along a predetermined direction. The second base layer 20 is sequentially provided with a second hydrophobic layer 21, a second dielectric layer 22, and a substrate layer 24 along a predetermined direction. Driving electrodes 23 are arranged on the side of the substrate layer 24 near the second dielectric layer 22. Multiple driving electrodes 23 are disposed on the substrate layer 24. The driving electrodes 23 are small in size, have a high density, and are located directly below the conductive liquid 40. The driving electrodes 23 are used to electrowet the conductive liquid 40. When a certain voltage is applied to the driving electrodes 23, the wettability of the conductive liquid 40 changes, allowing it to electrically connect with some of the metal wires 32. Through the interconnection of multiple conductive liquid 40 lattices and some of the metal wires 32, different metasurface configurations are formed.

[0053] The fluid medium layer 30 is mainly filled with fluid medium 31, which is uniformly distributed around the conductive liquid 40. The first hydrophobic layer 14, the first dielectric layer 13, and the electrode layer 12 are provided with fixing grooves 101 above the conductive liquid 40. There are multiple fixing grooves 101, and they are arranged in an array structure like the conductive liquid 40. The array structure of the fixing grooves 101 is the same as that of the conductive liquid 40. The fixing grooves 101 are arranged to fix the conductive liquid 40 in a plane position perpendicular to a preset direction.

[0054] like Figures 2 to 4 As shown, in some embodiments, the arrangement of the plurality of metal wires 32 forms a square, an equilateral triangle, or a regular hexagon. This embodiment only illustrates some arrangement methods between the metal wires 32 and the conductive liquid 40, wherein... Figure 2 It is an orthogonal arrangement, that is, a square arrangement or a cross arrangement. Figure 3 Arranged in regular hexagons, Figure 4 The square face-centered arrangement of the metal wires 32 with included angles of 90°, 60°, and 45° is suitable for different metasurface configurations.

[0055] like Figure 5 As shown, it can be understood that when the metal wires 32 are arranged in a square pattern, Figure 5 This is a schematic diagram of the connection scheme between the conductive liquid 40 and the metal wire 32, showing the layout of the driving electrode 23 around the conductive liquid 40, and listing all the electrical interconnection schemes that the conductive liquid 40 node can achieve under the current layout.

[0056] like Figures 6 to 8 As shown, when the metal wires 32 are orthogonally arranged and the driving electrodes 23 are in a cross-shaped layout, Figure 6 Taking a cross-shaped metasurface configuration as an example, this demonstrates several states of change in the geometry of the current configuration. The denser the dimensions of the metal wires 32 and the driving electrode 23, the more configuration states the cross-shaped configuration can have per unit area. Similarly, as... Figure 7 or Figure 8 As shown, the current layout of the metal wire 32 and the driving current 2 is also applicable to various configurations such as I-shaped, Jerusalem-shaped, and L-shaped, which can realize the reflection and transmission rates of different electromagnetic wave bands, as well as the polarization conversion of electromagnetic waves.

[0057] In some embodiments, the driving electrode 23 is made of aluminum, copper, platinum, silver, or titanium. The driving electrode 23 is fixedly arranged on the substrate layer 24 by printing; therefore, before sintering, the driving electrode 23 exists in the form of a fluid metal paste. Thus, the driving electrode 23 is generally made of high-melting-point precious metals such as aluminum, copper, platinum, silver, or titanium, requiring it to be able to sinter at a high temperature of approximately 1400°C without oxidation, melting, volatilization, or loss.

[0058] It is understandable that the driving electrode 23 is connected to a control programming system, which is used to control the magnitude and position of the voltage applied to the driving electrode 23.

[0059] In some embodiments, the substrate layer 24 is made of silicon or glass, the first dielectric layer 13 and the second dielectric layer 22 are made of dichloro-p-xylene dimer or silicon dioxide, and the first hydrophobic layer 14 and the second hydrophobic layer 21 are made of dichloro-p-xylene dimer or polytetrafluoroethylene.

[0060] The substrate 24 is made of silicon or glass because silicon and glass have higher melting temperatures that allow for a wider range of process tolerances.

[0061] The first dielectric layer 13 and the second dielectric layer 22 are made of dichloro-p-xylene dimer or silicon dioxide.

[0062] In some embodiments, the electrode layer 12 is made of indium tin oxide film, and the top substrate 11 is made of polymethyl methacrylate, polydimethylsiloxane, polyethylene terephthalate, polycarbonate, or glass.

[0063] It is understandable that the electrode layer 12 is made of indium tin oxide film, which is usually deposited on the surface of the first dielectric layer 13 by physical vapor deposition or some sputtering deposition techniques.

[0064] Understandably, the top substrate 11 is made of polymethyl methacrylate, polydimethylsiloxane, polyethylene terephthalate, polycarbonate or glass, and therefore the top substrate 11 generally has the characteristics of high transparency, low price and easy processing.

[0065] In some embodiments, the first hydrophobic layer 14 and the second hydrophobic layer 21 are prepared by thin film deposition or surface chemical grafting. Thin film deposition includes physical and chemical vapor deposition (PVD), molecular beam epitaxy (MBE), spin coating or spraying, and electroplating; PVD is commonly used. Surface chemical grafting can attach specified functional groups to the surface of the matrix polymer to be modified, thereby achieving a significant surface modification effect without affecting the bulk properties of the matrix polymer. Specifically, the first hydrophobic layer 14 is formed using surface chemical grafting on the first dielectric layer 13, or the second hydrophobic layer 21 is formed using surface chemical grafting on the second dielectric layer 22.

[0066] In some embodiments, the metal wire 32 is made of copper, platinum or gold, and the fluid medium of the fluid medium layer 30 is silicone oil or fluorinated liquid.

[0067] like Figure 9 As shown, the present invention also provides a control method for an electrowetting-based reconfigurable metasurface, used to control the aforementioned electrowetting-based reconfigurable metasurface, comprising the following steps:

[0068] Add conductive liquid 40 above the driving electrode 23;

[0069] The first base layer 10 is encapsulated above the driving electrode 23 along a preset direction;

[0070] Fill the fluid medium layer 30 with fluid medium 31 so that the conductive liquid 40 is encapsulated in the fluid medium 31;

[0071] A voltage is applied to the driving electrode 23, thereby changing the configuration of the metasurface.

[0072] In some embodiments, gallium indium tin alloy, mercury, or an ionic liquid is selected as the conductive liquid 40.

[0073] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A reconfigurable metasurface based on electrowetting, characterized in that, The reconfigurable metasurface based on electrowetting is provided with a first base layer, a fluid medium layer and a second base layer in sequence along a preset direction; The fluid medium layer contains a plurality of metal wires and is used to contain conductive liquid. The first base layer is provided with a top substrate, an electrode layer, a first dielectric layer and a first hydrophobic layer in sequence along the preset direction. The first hydrophobic layer, the first dielectric layer and the electrode layer are provided with fixing grooves above the conductive liquid. There are multiple fixing grooves and they are array structures like the conductive liquid. The array structure of the fixing grooves is the same as the array structure of the conductive liquid. The array of fixing grooves is used to fix the plane position of the conductive liquid perpendicular to the preset direction. The second base layer is provided with a second hydrophobic layer, a second dielectric layer and a substrate layer in sequence along the preset direction. The substrate layer is provided with a plurality of driving electrodes, which are arranged on the side of the substrate layer close to the second dielectric layer. The driving electrodes are located directly below the conductive liquid. The driving electrodes electrowet the conductive liquid. When a certain voltage is applied to the driving electrodes, the wettability of the conductive liquid changes, and it can be electrically connected to some of the metal wires. Different configurations of the metasurface are formed through the interconnection between the plurality of conductive liquid lattices and some of the metal wires.

2. The reconfigurable metasurface based on electrowetting according to claim 1, characterized in that, The arrangement of the plurality of said metal wires forms a square, an equilateral triangle, or a regular hexagon.

3. The reconfigurable metasurface based on electrowetting according to claim 1, characterized in that, The driving electrode is made of aluminum, copper, platinum, silver, or titanium.

4. The reconfigurable metasurface based on electrowetting according to claim 1, characterized in that, The substrate layer is made of silicon or glass; And / or, the first dielectric layer and the second dielectric layer are made of dichloro-p-xylene dimer or silicon dioxide; And / or, the first hydrophobic layer and the second hydrophobic layer are made of dichloro-p-xylene dimer or polytetrafluoroethylene.

5. The reconfigurable metasurface based on electrowetting according to claim 1, characterized in that, The electrode layer is made of indium tin oxide thin film; And / or, the material of the top substrate is polymethyl methacrylate, polydimethylsiloxane, polyethylene terephthalate, polycarbonate or glass.

6. The reconfigurable metasurface based on electrowetting according to claim 1, characterized in that, The first hydrophobic layer and the second hydrophobic layer are prepared by thin film deposition or surface chemical grafting.

7. The reconfigurable metasurface based on electrowetting according to claim 1, characterized in that, The metal wire is made of copper, platinum, or gold; And / or, the fluid medium of the fluid medium layer is silicone oil or fluorinated liquid.

8. A control method for an electrowetting-based reconfigurable metasurface, used to control the electrowetting-based reconfigurable metasurface as described in any one of claims 1-7, characterized in that, Includes the following steps: Add conductive liquid above the driving electrode; The first base layer is encapsulated above the driving electrode along a preset direction; Fill the fluid medium layer with a fluid medium so that the conductive liquid is encapsulated in the fluid medium; A voltage is applied to the driving electrode, thereby changing the configuration of the metasurface.

9. The control method for the reconfigurable metasurface according to claim 8, characterized in that, Gallium indium tin alloy, mercury, or ionic liquid is selected as the conductive liquid.

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