Adjustable metamaterial wave absorber based on microfluidics

Abstract

The invention belongs to the technical field of metamaterial wave absorption, and particularly relates to an adjustable metamaterial wave absorber based on microfluidics, which is formed by splicing a plurality of wave-absorbing units, each wave-absorbing unit comprises at least two layers of parallel microfluidic channel structures, and the parallel microfluidic channel structures are used for flowing of a wave-absorbing medium; two adjacent parallel microfluidic channel structures in the same horizontal direction are communicated; two adjacent parallel microfluidic channel structures are arranged in the middle of the resistive film resonance structure at intervals; and the metal grounding layer is connected to the bottom end of the resistive film resonance structure, and a spacing layer is arranged between the metal grounding layer and the end part of the resistive film resonance structure. Different wave-absorbing media are introduced into the at least two layers of parallel microfluidic channel structures, and switching of wave-absorbing states of the wave absorber can be realized by controlling injection and discharge of the wave-absorbing media.

Description

Technical Field

[0001] The present invention belongs to the technical field of metamaterial wave absorbers, and in particular relates to an adjustable metamaterial wave absorber based on microfluidics. Background Art

[0002] Electromagnetic metamaterials are a type of artificial material composed of sub-wavelength periodic structural units, which have unique electromagnetic phenomena not found in natural materials. The core idea of ​​metamaterials is to construct a unit structure that can produce a special electromagnetic response to incident waves, and its resonance mode and resonance frequency can be adjusted by the shape, geometric parameters and arrangement of the periodic units.

[0003] As the external electromagnetic environment becomes increasingly complex, the requirements for radar stealth are also getting higher and higher. Traditional absorbing metamaterials will not be able to make corresponding adjustments to the new electromagnetic environment, and the actual service life will be greatly shortened. At this time, absorbers with switching and tuning functions came into being. Compared with traditional absorbers, the characteristics of reconfigurable absorbers are their controllable characteristics, that is, the electromagnetic characteristics can change with the change of external excitation. The flexible and controllable characteristics make it widely adaptable and have broad application prospects. Therefore, we propose a microfluidic-based adjustable metamaterial absorber. Summary of the invention

[0004] The purpose of the present invention is to provide an adjustable metamaterial absorber based on microfluidics to solve the above problems.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A microfluidics-based adjustable metamaterial absorber is composed of a plurality of absorber units, wherein the absorber units include:

[0007] At least two layers of parallel microfluidic channel structures, the parallel microfluidic channel structures are used for the flow of absorbing medium; the parallel microfluidic channel structures of two adjacent absorbing units located in the same horizontal direction are connected; the two adjacent parallel microfluidic channel structures in the same absorbing unit are arranged at intervals in the middle of the resistive film resonant structure;

[0008] A metal grounding layer is connected to the bottom end of the resistor film resonant structure, and a spacer layer is provided between the metal grounding layer and the end of the resistor film resonant structure.

[0009] Optionally, the resistive film resonant structure includes a first resistive film resonant structure located at the top and a plurality of second resistive film resonant structures located between the first resistive film resonant structure and the metal grounding layer;

[0010] The bottom of the first resistive film resonant structure is fixedly connected to the top surface of the parallel microfluidic channel structure located at the top;

[0011] The second resistor film resonant structure is arranged between two adjacent parallel microfluidic channel structures, another second resistor film resonant structure is arranged between the parallel microfluidic channel structure at the bottom and the metal grounding layer, and the second resistor film resonant structure at the bottom is connected to the metal grounding layer through the spacer layer.

[0012] Optionally, the parallel microfluidic channel structure comprises a dielectric substrate, two ends of the dielectric substrate are respectively provided with communication ports, a microfluidic channel is provided in the middle of the dielectric substrate, and the microfluidic channel is used for the flow of the absorbing medium;

[0013] Two adjacent parallel microfluidic channel structures located in the same horizontal direction are connected through the connecting port.

[0014] Optionally, the first resistive film resonant structure comprises a first absorbing plate, the bottom of the first absorbing plate is fixedly connected to the top surface of the parallel microfluidic channel structure at the top, and a cross-shaped resistive film is attached to the center of the top surface of the first absorbing plate.

[0015] Optionally, the second resistive film resonant structure includes a second absorbing patch, a square ring-shaped resistive film is attached to the top edge of the second absorbing patch, the second absorbing patch is fixedly connected to the parallel microfluidic channel structure, and the bottom surface of the second absorbing patch at the bottom is fixedly connected to the metal grounding layer through the spacer layer.

[0016] Optionally, the spacer layer is an air layer or a foam layer.

[0017] Optionally, the absorbing medium is water or liquid metal.

[0018] Optionally, the liquid metal is a gallium-indium alloy.

[0019] Optionally, the parallel microfluidic channel structure is provided with two layers.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects:

[0021] When in use, different absorbing media are introduced into at least two layers of parallel microfluidic channel structures, and the absorbing state of the absorber can be switched by controlling the injection and discharge of the absorbing media.

[0022] The present invention utilizes the state of liquid metal and water in a microfluidic channel to achieve reconfigurable electromagnetic properties, which can avoid the bulky mechanical tuning structure and the difficulty in integration with the FSS structure, eliminate the need for the design and use of additional bias circuits, and greatly reduce parasitic effects caused by the use of active devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative labor:

[0024] Figure 1 It is a schematic diagram of the structure of a single unit of the absorber of the present invention;

[0025] Figure 2 A diagram showing a first resistor film resonance structure and a second resistor film resonance structure of the present invention;

[0026] Figure 3 This is a structural diagram of the parallel microfluidic channels of the present invention;

[0027] Figure 4 A top view of the parallel microfluidic channel structure of the present invention;

[0028] Figure 5 Graphs showing the reflection coefficient of the present invention under five working conditions at a vertical incident angle;

[0029] Figure 6 is a reflection coefficient curve diagram of the present invention under the second working mode at an oblique angle;

[0030] Figure 7 is a reflection coefficient curve diagram of the fourth working mode at an oblique angle of the present invention;

[0031] Among them, 1. a first resistor film resonant structure; 2. an air layer; 3. a parallel microfluidic channel structure; 4. a metal grounding layer; 5. a second resistor film resonant structure. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Reference Figures 1 to 7 The present invention discloses a microfluidic-based adjustable metamaterial absorber, which is composed of a plurality of absorber units, and the absorber units include:

[0035] At least two layers of parallel microfluidic channel structures 3, the parallel microfluidic channel structures 3 are used for the flow of absorbing medium; the parallel microfluidic channel structures 3 of two adjacent absorbing units located in the same horizontal direction are connected; two adjacent parallel microfluidic channel structures 3 in the same absorbing unit are arranged at intervals in the middle of the resistive film resonant structure;

[0036] The metal grounding layer 4 is connected to the bottom end of the resistor film resonance structure, and a spacer layer is provided between the metal grounding layer 4 and the end of the resistor film resonance structure.

[0037] When in use, different absorbing media are introduced into at least two layers of the parallel microfluidic channel structure 3, and the absorbing state of the absorber can be switched by controlling the injection and discharge of the absorbing media.

[0038] As an optional implementation, the resistance film resonant structure includes a first resistance film resonant structure 1 located at the top and a plurality of second resistance film resonant structures 5 located between the first resistance film resonant structure 1 and the metal grounding layer 4;

[0039] The bottom of the first resistive film resonant structure 1 is fixedly connected to the top surface of the parallel micro-channel structure 3 located at the top;

[0040] The second resistance film resonant structure 5 is arranged between two adjacent parallel microfluidic channel structures 3, another second resistance film resonant structure 5 is arranged between the parallel microfluidic channel structure 3 at the bottom and the metal grounding layer 4, and the second resistance film resonant structure 5 at the bottom is connected to the metal grounding layer 4 through a spacer layer.

[0041] As an optional embodiment, the parallel microfluidic channel structure 3 includes a dielectric substrate, two ends of the dielectric substrate are respectively provided with communication ports, and a microfluidic channel is provided in the middle of the dielectric substrate, and the microfluidic channel is used for the flow of the absorbing medium;

[0042] The microfluidic channel has various shapes, and the microfluidic channel can be selected to be rectangular, circular, tubular, triangular, etc.

[0043] In this embodiment, the microfluidic channel includes multiple microfluidic channels, which are arranged in parallel and parallel to the horizontal direction of the dielectric substrate. Two adjacent microfluidic channels are isolated from each other, and the ends of several microfluidic channels are connected to the connecting port.

[0044] Two adjacent parallel microfluidic channel structures 3 located in the same horizontal direction are connected through a communication port.

[0045] The dielectric substrate of the parallel microfluidic channel structure 3 is made of polydimethylsiloxane with a relative dielectric constant of 2.72 and a loss tangent of 0.0027. The thickness of the parallel microfluidic channel structure 3 is 0.5 mm.

[0046] As an optional implementation, the first resistive film resonant structure 1 includes a first absorbing plate, the bottom of the first absorbing plate is fixedly connected to the top surface of the parallel microfluidic channel structure 3 located at the top, and a cross-shaped resistive film is attached to the center of the top surface of the first absorbing plate.

[0047] As an optional embodiment, the second resistive film resonant structure 5 includes a second absorbing patch, a square ring-shaped resistive film is attached to the top edge of the second absorbing patch, the second absorbing patch is fixed to the parallel microfluidic channel structure 3, and the bottom surface of the second absorbing patch at the bottom is fixed to the metal grounding layer 4 through a spacer layer.

[0048] Furthermore, the absorber unit period of the device is p=10 mm, and the total thickness of the structure is 7 mm.

[0049] As an additional implementation, the first resistive film resonant structure 1 is composed of a cross-shaped resistive film and a first absorbing patch made of YW1_63%, with a thickness of =0.5mm, a length of =8mm, a width of =2mm, and a square resistance of =100Ω / sq;

[0050] The second resistor film resonant structure 5 located in the middle is composed of a first square ring type resistive film and a second wave absorbing patch made of P3_42%, with a thickness of 0.5 mm, an outer ring side length of the first square ring type resistive film of 10 mm, an inner ring side length of 9 mm, and a square resistance of 100 Ω / sq;

[0051] The second absorbing patch of the second resistive film resonant structure 5 located at the top is composed of a third ring-shaped resistive film and a third absorbing patch made of P3_63%, with a thickness of = 0.5mm; the outer ring side length of the third ring-shaped resistive film is = 10mm, the inner ring side length is = 9mm, and the square resistance is = 50Ω / sq.

[0052] As an optional implementation, the spacer layer is an air layer or a foam layer.

[0053] The thickness of the air layer is 2 mm.

[0054] As an optional implementation, the absorbing medium is water or liquid metal.

[0055] As an optional implementation, the liquid metal is a gallium-indium alloy.

[0056] As an optional implementation, the parallel microfluidic channel structure 3 is provided with two layers.

[0057] According to the injection / emptying states of liquid metal and water in the upper parallel microfluidic channel structure 3 and the lower parallel microfluidic channel structure 3, the device has five working states, namely, "first absorbing mode" (both the upper and lower microfluidic channels are emptied), "second absorbing mode" (the upper microfluidic channel is emptied, and the lower microfluidic channel is injected with liquid metal), "third absorbing mode" (the upper microfluidic channel is injected with liquid metal, and the lower microfluidic channel is emptied), "fourth absorbing mode" (both the upper and lower microfluidic channels are injected with liquid metal) and "fifth absorbing mode" (both the upper and lower microfluidic channels are injected with water).

[0058] The test surface shows that <1> In the “first absorption mode” (the upper and lower microfluidic channels are both empty), the effective absorption bandwidth is 3.24GHz-6.32GHz and 14.2GHz-16.53GHz;

[0059] <2> In the "second absorption mode" (the upper microfluidic channel is emptied and the lower microfluidic channel is injected with liquid metal), the effective absorption bandwidth is 4.91GHz-8.81GHz;

[0060] <3> In the “third absorption mode” (liquid metal is injected into the upper microfluidic channel and the lower microfluidic channel is emptied), the effective absorption bandwidth is 7.73GHz-11.21GHz and 13.46GHz-16.59GHz;

[0061] <4> In the “fourth absorption mode” (liquid metal is injected into both the upper and lower microfluidic channels), the effective absorption bandwidth is 8.3 GHz-12.81 GHz;

[0062] <5> In the "fifth absorption mode" (water is injected into both the upper and lower microfluidic channels), the effective absorption bandwidth is 2.97GHz-5.14GHz and 11.86GHz-13.82GHz.

[0063] At an oblique incidence of 45°, the effective absorption bandwidths in the "second absorbing mode" and "fourth absorbing mode" are 5.58GHz-8.39GHz and 9GHz-11.62GHz respectively.

[0064] The above results show that by controlling the injection and drainage of liquid metal and water in the double-layer parallel microfluidic channel structure, the structure designed by the present invention can realize switching between multiple independent working states, and has the advantage of multi-frequency broadband frequency tuning under effective wave absorption state in the 2-18GHz frequency band, and the effective wave absorption covers 3-16.5GHz, while still showing good performance at 45° oblique incidence.

[0065] The wave absorbing principle of the present invention mainly includes three parts: the first part is that after the electromagnetic wave is incident on the resistor film, the wave absorbing patch and the microfluidic channel, the electromagnetic wave is lost in the form of electromagnetic loss; the second part is that the reflected wave of the electromagnetic wave incident on the surface of the absorber and the wave incident on the absorber propagates inside and finally propagates to the surface of the structure after being reflected on the metal grounding bottom plate at the bottom of the structure, interfere with each other and are lost; the third part is that the electromagnetic wave is incident on the absorber and undergoes multiple reflections and refractions, and is finally lost in the form of scattering loss.

[0066] Compared with the prior art, the present invention has the following significant advantages: the present invention utilizes the state of liquid metal and water in a microfluidic channel to achieve reconfigurable electromagnetic properties, which can avoid the bulky mechanical tuning structure and the difficulty in integrating with the FSS structure, and does not require the design and use of additional bias circuits, and greatly reduces the parasitic effects caused by the use of active devices. The high conductivity and excellent fluidity of liquid metal also make it possible to have functions such as adjustable electromagnetic absorption characteristics.

[0067] The absorber has good absorbing performance in the frequency band of 2-18GHz, can achieve multi-frequency broadband tunability, and effectively absorbs waves covering 3-16.5GHz.

[0068] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0069] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A microfluidics-based adjustable metamaterial absorber, characterized in that: It is composed of several absorbing units, and the absorbing units include: At least two layers of parallel microfluidic channel structures (3), the parallel microfluidic channel structures (3) are used for the flow of absorbing media; the parallel microfluidic channel structures (3) of two adjacent absorbing units located in the same horizontal direction are connected; and the two adjacent parallel microfluidic channel structures (3) in the same absorbing unit are arranged at intervals in the middle of the resistive film resonant structure; A metal grounding layer (4) is connected to the bottom end of the resistive film resonant structure, and a spacer layer is provided between the metal grounding layer (4) and the end of the resistive film resonant structure.

2. The microfluidics-based adjustable metamaterial absorber according to claim 1, characterized in that: The resistance film resonant structure comprises a first resistance film resonant structure (1) located at the top and a plurality of second resistance film resonant structures (5) located between the first resistance film resonant structure (1) and the metal grounding layer (4); The bottom of the first resistive film resonant structure (1) is fixedly connected to the top surface of the parallel microfluidic channel structure (3) located at the top; The second resistor film resonant structure (5) is arranged between two adjacent parallel microfluidic channel structures (3), another second resistor film resonant structure (5) is arranged between the parallel microfluidic channel structure (3) at the bottom and the metal grounding layer (4), and the second resistor film resonant structure (5) at the bottom and the metal grounding layer (4) are connected via the spacer layer.

3. The microfluidics-based adjustable metamaterial absorber according to claim 1, characterized in that: The parallel microfluidic channel structure (3) comprises a dielectric substrate, two ends of the dielectric substrate are respectively provided with communication ports, a microfluidic channel is provided in the middle of the dielectric substrate, and the microfluidic channel is used for the flow of the absorbing medium; Two adjacent parallel microfluidic channel structures (3) located in the same horizontal direction are connected via the connecting port.

4. The microfluidics-based adjustable metamaterial absorber according to claim 2, characterized in that: The first resistive film resonant structure (1) comprises a first absorbing plate, the bottom of which is fixedly connected to the top surface of the parallel microfluidic channel structure (3) located at the top, and a cross-shaped resistive film is attached to the center of the top surface of the first absorbing plate.

5. The microfluidics-based adjustable metamaterial absorber according to claim 2, characterized in that: The second resistive film resonant structure (5) comprises a second absorbing patch, a square ring-shaped resistive film is attached to the top edge of the second absorbing patch, the second absorbing patch is fixedly connected to the parallel microfluidic channel structure (3), and the bottom surface of the second absorbing patch at the bottom is fixedly connected to the metal grounding layer (4) via the spacer layer.

6. The microfluidics-based adjustable metamaterial absorber according to claim 1, characterized in that: The spacer layer is an air layer or a foam layer.

7. The microfluidics-based adjustable metamaterial absorber according to claim 1, characterized in that: The wave absorbing medium is water or liquid metal.

8. The microfluidics-based adjustable metamaterial absorber according to claim 7, characterized in that: The liquid metal is a gallium-indium alloy.

9. The microfluidics-based adjustable metamaterial absorber according to claim 1, characterized in that: The parallel microfluidic channel structure (3) is provided with two layers.

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