Liquid metal micro-channel structure and reconfigurable metasurface reflection unit

Abstract

The invention relates to a liquid metal micro-channel structure and a reconfigurable metasurface reflection unit, and belongs to the technical field of artificial electromagnetic materials. The problems that when an existing micro-channel structure is applied to a metasurface reflection unit, the regulation and control state is discrete and limited, the continuous adjustment capacity is insufficient, the adjustment bandwidth is narrow, and the reflection phase shift range is small are solved. A liquid metal micro-channel structure comprises a plurality of unit micro-channel structures, and each unit micro-channel structure is of a bent cross-shaped structure and comprises a liquid storage tank and four semicircular cross arm channels. A fixed metal array of a conventional metasurface structure is replaced by a micro-channel array composed of liquid metal and a plurality of semicircular cross arm type unit micro-channel structures, and continuous reconfiguration of the metasurface reflection unit structure is achieved by controlling continuous adjustability of the liquid metal in semicircular cross arm channels. The antenna has the characteristics of polarization insensitivity, incident angle insensitivity and large reflection phase shift range.

Description

Technical Field

[0001] The present invention relates to the technical field of artificial electromagnetic materials, and in particular to a liquid metal microchannel structure and a reconfigurable supersurface reflection unit. Background Art

[0002] Liquid metal is an amorphous, conductive metal that can flow at room temperature. It combines the excellent properties of traditional rigid and flexible materials. In recent years, with the continuous development of liquid metal performance, the ratio of different alloy materials can achieve different viscosity, melting point, conductivity and other performance characteristics. The large deformation and fluidity of liquid metal are integrated with microstructures to achieve the filling, injection and microflow of liquid metal in microchannel structures. It has the characteristics of flexibility, low cost and reconfigurability, and has become an emerging technology with great development prospects. It can be widely used in flexible electronics, flexible sensors, reconfigurable antennas, metamaterials and other fields.

[0003] By taking advantage of the arbitrary fluidity of liquid metal and preparing a microfluidic packaging structure to allow the liquid metal to flow in the flow channel, it can replace the solid metal part in the metasurface structure. By controlling its flow in the flow channel, the continuous reconfiguration of the electromagnetic response state can be achieved. In order to achieve the distribution morphology of liquid metal in the flow channel structure, it is necessary to drive and control the precise flow control characteristics of the liquid metal in the flow channel structure. However, the existing application of liquid metal in microfluidic structure is still in its infancy, and there are few reports on the influence of the shape of liquid metal in microfluidic structure on the performance of metasurface. In the existing microfluidic structure, the liquid metal size adjustment range is small and the reflection phase adjustment range is small. Summary of the invention

[0004] In view of the above analysis, the embodiments of the present invention aim to provide a liquid metal microfluidic structure and a reconfigurable metasurface reflection unit to solve at least one of the following problems of the existing liquid metal microfluidic structure and metasurface reflection unit structure: 1. The existing microfluidic structure is applied to the reconfigurable metasurface reflection unit, and the control state is discrete and limited; 2. The existing microfluidic structure is applied to the reconfigurable metasurface reflection unit, and the continuous adjustment capability is insufficient and the adjustment bandwidth is narrow; 3. The existing microfluidic structure is applied to the reconfigurable metasurface reflection unit, and the reflection phase shift range is small.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions:

[0006] On the one hand, the present invention provides a liquid metal microfluidic channel structure, including a plurality of unit microfluidic channel structures, wherein the unit microfluidic channel structure is a curved cross-shaped structure, including a liquid storage tank and four semicircular cross-arm flow channels.

[0007] Furthermore, the liquid metal microfluidic channel structure is an array structure, the array structure includes a plurality of periodically arranged sub-array structures, the sub-array structure includes N*N unit microfluidic channel structures, 3≤N≤5.

[0008] Furthermore, the unit microfluidic channel structures are interconnected, and the sub-array structures are independent of each other and not interconnected.

[0009] Furthermore, the arrangement period of the unit microfluidic channel structure is P, wherein P is 13-17 mm.

[0010] Furthermore, the arrangement period of the sub-array structure is Px, wherein Px satisfies: NP<Px≤(N+1)P.

[0011] Furthermore, the liquid reservoir is located in the center of the microfluidic channel structure, the four semicircular cross-arm flow channels are arranged around the liquid reservoir, and are interconnected through the liquid reservoir, and the four semicircular cross-arm flow channels all extend in a direction away from the liquid reservoir.

[0012] Further, the four semicircular cross-arm flow channels include a first semicircular cross-arm flow channel, a second semicircular cross-arm flow channel, a third semicircular cross-arm flow channel and a fourth semicircular cross-arm flow channel;

[0013] The first semicircular arc cross arm flow channel and the third semicircular arc cross arm flow channel are centrally symmetrically distributed, and the second semicircular arc cross arm flow channel and the fourth semicircular arc cross arm flow channel are centrally symmetrically distributed.

[0014] Furthermore, the angle between the first semicircular arc cross arm flow channel and the second semicircular arc cross arm flow channel is 90°, the angle between the second semicircular arc cross arm flow channel and the third semicircular arc cross arm flow channel is 90°, the angle between the third semicircular arc cross arm flow channel and the fourth semicircular arc cross arm flow channel is 90°, and the angle between the fourth semicircular arc cross arm flow channel and the first circular arc cross arm flow channel is 90°.

[0015] Furthermore, the width w1 of the semicircular cross-arm flow channel is 0.2-0.6 mm, the arc radius r1 of the semicircular cross-arm flow channel is 3-3.5 mm, and the width l1 of the liquid storage tank is 1.5-2.5 mm.

[0016] On the other hand, the present invention also provides a liquid metal reconfigurable metasurface reflection unit, comprising the above-mentioned liquid metal microfluidic channel structure.

[0017] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0018] 1. The present invention provides a liquid metal microfluidic channel structure, comprising a plurality of unit microfluidic channel structures, wherein the unit microfluidic channel structure is a curved cross-shaped structure, comprising a liquid storage tank and four semicircular cross-arm flow channels, and the present invention can solve the problems of a small liquid metal size adjustment range, insufficient continuous adjustment capability, and narrow adjustment bandwidth in existing microfluidic channel structures by controlling the continuous adjustment of the liquid metal in the semicircular cross-arm flow channels.

[0019] 2. The present invention replaces the fixed metal array of the conventional metasurface structure with a microfluidic channel array composed of liquid metal and a plurality of semicircular cross-arm unit microfluidic channel structures. By setting a driving control unit with the same number as the sub-array structures in the liquid metal microfluidic channel structure, each driving control unit is set in a one-to-one correspondence with each sub-array structure, and each driving control unit independently controls the flow position and shape of the liquid metal in the sub-array microfluidic channel corresponding to it. By controlling the continuous adjustability of the liquid metal in the semicircular cross-arm channel, the resonant frequency and reflection phase of the reflection unit can be continuously reconfigured, thereby solving the problems faced by conventional metasurface units that use components such as PIN diodes to adjust the electromagnetic response state, such as limited control state and insufficient continuous adjustment capability.

[0020] 3. The liquid metal microfluidic channel structure of the present invention is applied to the reconfigurable metasurface reflection unit. By bending the flow channel of the cross-shaped structure, the size adjustment range of the liquid metal is increased, and the adjustment range of the reflection phase is expanded. It has the functions of polarization insensitivity, incident angle insensitivity, continuous adjustable electromagnetic response, and continuous adjustable reflection phase over a large range. It can be applied to radar camouflage stealth, dynamic reconfigurable communication and other fields.

[0021] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0023] Figure 1 This is a distribution diagram of liquid metal and driving liquid in a liquid metal unit microchannel structure according to an embodiment of the present invention;

[0024] Figure 2 A top view of a liquid metal unit microchannel structure according to an embodiment of the present invention;

[0025] Figure 3 A top view of a liquid metal subarray microfluidic channel structure according to an embodiment of the present invention;

[0026] Figure 4 A cross-sectional view of a liquid metal reconfigurable metasurface reflective unit according to an embodiment of the present invention;

[0027] Figure 5 Schematic diagram of the flow of liquid metal in a unit microchannel structure according to an embodiment of the present invention;

[0028] Figure 6 A frequency dynamic reconfigurable graph of a liquid metal reflection unit according to an embodiment of the present invention;

[0029] Figure 7 This is a reflection phase range diagram of the liquid metal reflection unit according to an embodiment of the present invention;

[0030] Figure 8 A top view of a unit microchannel structure of a liquid metal reflection unit of a comparative example;

[0031] Fig. 9 It is the frequency dynamic reconfigurable diagram of the comparative liquid metal reflection unit;

[0032] Fig.10 is a reflection phase range diagram of a comparative liquid metal reflection unit;

[0033] Fig.11 A comparison diagram of the reflection phase range of the liquid metal reflection unit of the embodiment of the present invention and the comparative example;

[0034] Fig.12 is the center frequency (f) of the liquid metal reflector unit under X and Y polarization in the embodiment of the present invention 0＝ 8GHz) reflection phase contrast diagram;

[0035] Fig.13 is the center frequency (f) of the liquid metal reconfigurable metasurface reflection unit under different incident angles in the embodiment of the present invention. 0＝ 8GHz) reflection phase contrast diagram.

[0036] Reference numerals:

[0037] 1-liquid metal; 2-liquid metal microfluidic channel structure; 21-liquid reservoir; 22-first semicircular cross-arm channel; 23-second semicircular cross-arm channel; 24-third semicircular cross-arm channel; 25-fourth semicircular cross-arm channel; 3-driving liquid; 4-flexible substrate; 5-flexible film; 6-flexible upper cover plate; 7-air cavity structure; 8-driving control structure; 9-ground plate;

[0038] P-arrangement period of unit microfluidic structure; Px-arrangement period of sub-array microfluidic structure; d-bonding width between sub-array microfluidic structures; w1-width of semicircular cross-arm flow channel of unit microfluidic structure; r1-arc radius of semicircular cross-arm flow channel; l1-width of liquid reservoir; t1-height of liquid metal microfluidic structure; h1-thickness of flexible substrate; h2-thickness of flexible upper cover plate; t2-air cavity structure 7; J-arc angle of liquid metal when flowing in the semicircular cross-arm flow channel of unit microfluidic structure. DETAILED DESCRIPTION

[0039] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0040] The present invention provides a liquid metal microfluidic channel structure, comprising a plurality of unit microfluidic channel structures, wherein the unit microfluidic channel structure is a bent cross-shaped structure, comprising a liquid storage tank and four semicircular cross-arm flow channels.

[0041] The present invention can solve the problems of small liquid metal size adjustment range, insufficient continuous adjustment capability and narrow adjustment bandwidth of the existing microchannel structure by controlling the continuous adjustment of liquid metal in the semicircular arc cross-arm flow channel.

[0042] The liquid metal microfluidic channel structure is an array structure, the array structure includes a plurality of periodically arranged sub-array structures, the sub-array structure includes N*N unit microfluidic channel structures, wherein 3≤N≤5;

[0043] The arrangement period of the unit microfluidic channel structure is P, where P is 13-17 mm;

[0044] The arrangement period of the sub-array structure is Px, where Px satisfies: NP<Px≤(N+1)P; the sub-array microfluidic channel structures are independent of each other and are not connected; illustratively, Figure 3 As shown, the sub-array structure includes 3*3 unit microfluidic channel structures, where d is the bonding width between the sub-array microfluidic channel structures, which is generally 2-4 mm, and Px is 43-59 mm.

[0045] The present invention can replace the fixed metal array of the conventional metasurface structure by adopting a microfluidic channel array composed of liquid metal and a plurality of semicircular cross-arm unit microfluidic channel structures. By setting a driving control unit with the same number as the subarray structures in the liquid metal microfluidic channel structure, each driving control unit is set in a one-to-one correspondence with each subarray structure, and each driving control unit independently controls the flow position and shape of the liquid metal in the subarray microfluidic channel corresponding thereto. By controlling the continuous adjustability of the liquid metal in the semicircular cross-arm channel, the resonant frequency and the reflection phase of the reflection unit can be continuously reconfigured, thereby solving the problems of limited control state and insufficient continuous adjustment capability faced by conventional metasurface units when using components such as PIN diodes to adjust the electromagnetic response state.

[0046] The unit microchannel structures are interconnected and are in the shape of a curved cross, including a liquid reservoir and four semicircular cross-arm channels; Figure 1 As shown, the liquid reservoir 21 is located in the center of the unit microfluidic channel structure, the four semicircular cross-arm flow channels are arranged around the liquid reservoir, and are interconnected through the liquid reservoir, and the four semicircular cross-arm flow channels all extend in the direction away from the liquid reservoir; the four semicircular cross-arm flow channels include a first semicircular cross-arm flow channel 22, a second semicircular cross-arm flow channel 23, a third semicircular cross-arm flow channel 24 and a fourth semicircular cross-arm flow channel 25; the first semicircular cross-arm flow channel 22 and the third semicircular cross-arm flow channel 24 are symmetrically distributed in the center, and the second semicircular cross-arm flow channel 23 is symmetrically distributed in the center. The cross arm channel 23 and the fourth semicircular cross arm channel 25 are symmetrically distributed around the center; the angle between the first semicircular cross arm channel 22 and the second semicircular cross arm channel 23 is 90°, the angle between the second semicircular cross arm channel 23 and the third semicircular cross arm channel 24 is 90°, the angle between the third semicircular cross arm channel 24 and the fourth semicircular cross arm channel 25 is 90°, and the angle between the fourth semicircular cross arm channel 25 and the first circular cross arm channel 22 is 90°.

[0047] The specific parameters of the liquid metal microfluidic channel structure are: the width w1 of the semicircular cross-arm channel of the unit microfluidic channel structure is 0.2-0.6 mm, the arc radius r1 of the semicircular cross-arm channel is 3-3.5 mm, the width l1 of the liquid reservoir is 1.5-2.5 mm, and the height t1 of the liquid metal microfluidic channel structure is 0.05-0.3 mm.

[0048] The liquid metal microfluidic channel structure of the present invention is applied to a reconfigurable metasurface reflection unit. The liquid metal size adjustment range is increased by bending the flow channel of the cross-shaped structure, and the reflection phase adjustment range is expanded. It has the functions of polarization insensitivity, incident angle insensitivity, continuously adjustable electromagnetic response, and continuously adjustable reflection phase over a large range. It can be applied to radar camouflage stealth, dynamic reconfigurable communications and other fields.

[0049] Based on this, the present invention also provides a liquid metal reconfigurable metasurface reflection unit, comprising the above-mentioned liquid metal microchannel structure;

[0050] The liquid metal reconfigurable metasurface reflection unit further includes: a flexible substrate 4, a flexible film 5, a flexible upper cover plate 6, a driving control structure 8 and a ground plate 9;

[0051] The flexible upper cover plate 6, the flexible film 5, the flexible substrate 4, the ground plate 9 and the drive control structure 8 are stacked in sequence;

[0052] The liquid metal microfluidic channel structure is arranged on a flexible substrate 4, the flexible film 5 is bonded to the flexible substrate 4 by hot pressing, the flexible upper cover plate 6 is bonded to the flexible film 5 by spraying glue, and an air cavity structure 7 identical to the unit microfluidic channel structure is provided in the flexible upper cover plate 6;

[0053] The driving control structure 8 includes the same number of driving control units as the sub-array structures in the liquid metal microfluidic channel structure, each driving control unit is arranged in a one-to-one correspondence with each sub-array structure, and each driving control unit independently controls the flow position and shape of the liquid metal in the corresponding sub-array microfluidic channel. In the sub-array microfluidic channel, the liquid metal control length in each unit microfluidic channel is the same;

[0054] The flexible substrate 4 is provided with the same number of injection ports as the sub-array structures in the liquid metal microfluidic channel structure, each injection port is provided in a one-to-one correspondence with each sub-array structure, and the driving control unit is connected to the injection port on the flexible substrate 4 through an external conduit, so as to control the flow state of the liquid metal in the multiple unit microfluidic channel structures, such as position and shape;

[0055] The two sides of the ground plate 9 are respectively glued to the flexible substrate 4 and the drive control structure 8 .

[0056] Specifically, the flexible substrate 4, the flexible film 5, and the flexible upper cover plate 6 together form a flexible packaging structure, the thickness h1 of the flexible substrate 4 is 3-6 mm, the thickness of the flexible film 5 is 10-50 μm, and the thickness h2 of the flexible upper cover plate 6 is 1.5-3 mm;

[0057] Specifically, the flexible film 5 is bonded to the flexible substrate by heat compression, so as to seal the liquid metal 1 and the driving liquid 3 to avoid leakage.

[0058] Specifically, an air cavity structure 7 having the same structure as the unit microfluidic channel structure is manufactured in the flexible upper cover plate 6. The height t2 of the air cavity structure 7 is 0.7-1.2 mm, which is slightly higher than the height t1 of the microfluidic channel array structure to accommodate the volume changes of the liquid in the multiple unit microfluidic channel structures.

[0059] It should be noted that the liquid metal microfluidic channel structure 2 is disposed on a flexible substrate 4. Figure 1 and Figure 4 As shown, the liquid metal 1 is distributed in the liquid storage tank 21 and the four semicircular cross-arm flow channels connected to the liquid storage tank, and the driving liquid is distributed at the ends of the four semicircular cross-arm flow channels; the multiple unit microfluidic channel structures in the subarray, under the pressure drive of each driving control unit, the driving liquid 3 drives the liquid metal 1 to flow continuously in the multiple unit microfluidic channel structures, and changes at different flow positions and shapes in the four semicircular cross-arm flow channels of the multiple unit microfluidic channel structures, thereby reconstructing the structural morphology of the liquid metal 1. Each change in the flow position and shape of the liquid metal 1 in the microfluidic channel structure corresponds to a working state of the metasurface, so as to realize dynamic adjustment of the metasurface performance under multiple states. The size change range of the liquid metal when flowing in the semicircular cross-arm flow channel in the liquid metal reconfigurable metasurface reflection unit is 30°<J<180°, where J is the arc angle of the liquid metal when flowing in the semicircular cross-arm flow channel (such as Figure 1 The size and shape changes of liquid metal will change its resonant structure, which will lead to changes in its response frequency, reflection phase and working state, making it possible to dynamically reconfigure the resonant frequency in the C and X bands and continuously and dynamically adjust the reflection phase.

[0060] The liquid metal microfluidic structure 2 is prepared on a flexible substrate 4, and the unit resonant structure and its size parameters of the unit microfluidic structure are designed by comprehensively considering the relative dielectric constant, loss tangent, and conductivity material parameters of the flexible substrate, liquid metal, and driving liquid. In order to increase the control range of the reflection phase of the metasurface unit, the unit resonant structure is designed as a semicircular cross arm structure, which increases the adjustment range of the liquid metal resonance part and broadens the control range of the reflection phase; and according to the unit resonant structure and the flow mode of the liquid metal, a square liquid storage tank is designed at the center connection of the semicircular cross arm flow channel structure to facilitate the storage of liquid when injecting the driving liquid. The unit microfluidic structure is realized by micro-nano processing technology, including photolithography, nanoimprinting and other process methods.

[0061] Optionally, the flexible substrate 4 , the flexible film 5 , and the flexible upper cover plate 6 are made of materials such as PDMS, PMMA, SEBS, and PET.

[0062] Optionally, the liquid metal is a gallium-indium-tin alloy.

[0063] Optionally, the driving liquid is an alkaline solution, preferably, the alkaline solution is a NaOH solution, and the NaOH driving liquid is injected into the microchannel array structure through the injection port on the flexible substrate 4 before the liquid metal 1. The early injection of the driving liquid can play a wetting role, facilitate the flow of the liquid metal, and also remove the oxide layer on the surface of the liquid metal.

[0064] Optionally, the material of the ground plate 9 is metal, which is used to reflect electromagnetic waves, and materials such as aluminum and copper may be used.

[0065] The present invention also provides a method for manufacturing a liquid metal reconfigurable metasurface reflection unit, which is used to manufacture the liquid metal reconfigurable metasurface reflection unit, comprising the following steps:

[0066] S1: determining the shape and initial size of a unit microfluidic channel structure, wherein the unit microfluidic channel structure is a semicircular cross arm structure;

[0067] S2: According to the shape, initial size and initial arrangement period of the unit microfluidic structure, the subarray microfluidic structure and the liquid metal microfluidic structure are designed. According to the liquid metal microfluidic structure, the shape and initial size of the flexible substrate and the flexible upper cover are designed;

[0068] S3: Input the shape, initial size and initial arrangement period of the unit microfluidic channel structure, the shape and initial size of the flexible substrate and the flexible upper cover plate, and the initial size of the flexible film into the electromagnetic simulation software to obtain the initial metasurface reflection unit model;

[0069] S4: Input the material parameters of the flexible substrate, liquid metal and driving liquid, use electromagnetic simulation software to perform multiple parameter sweep iterations on the initial metasurface reflection unit model, obtain the final metasurface reflection unit model, and determine the dimensions of the unit microfluidic structure, flexible substrate, flexible film and flexible upper cover in the final metasurface reflection unit model as the final dimensions;

[0070] S5: According to the final metasurface reflection unit model, a unit microfluidic structure, a flexible substrate and a flexible upper cover plate that meet the shape and size requirements are manufactured;

[0071] S6: Fabrication of liquid metal microfluidic structures and injection ports on flexible substrates;

[0072] S7: According to the final metasurface reflection unit model, a flexible film is bonded on a flexible substrate by using a hot pressing method; an air cavity structure having the same shape as the unit microchannel structure is opened in the flexible upper cover plate;

[0073] S8: injecting a driving liquid through the injection port, and the driving liquid is injected into the flow channel of each unit microfluidic channel structure in the subarray microfluidic channel through the through holes between the unit microfluidic channel structures; injecting liquid metal through the injection port, and the liquid metal is injected into the flow channel of each unit microfluidic channel structure in the subarray microfluidic channel through the through holes between the unit microfluidic channel structures;

[0074] S9: The flexible upper cover is bonded to the flexible film by spraying glue; a ground plate is set under the flexible substrate; driving control units with the same number as the sub-array microchannels are set under the ground plate to form a driving control structure, and each driving control unit is connected to a corresponding injection port to obtain a physical metasurface reflection unit.

[0075] Specifically, in step S1, according to the requirements of polarization insensitivity and incident angle insensitivity of the metasurface reflection unit, combined with the fluidic properties of liquid metal, the shape and initial size of the unit microfluidic structure are designed.

[0076] Specifically, in step S4, the material parameters of the flexible substrate, liquid metal and driving liquid include the relative dielectric constant, loss tangent and conductivity of the material; when the metasurface reflection unit model simultaneously satisfies: the resonant frequency of the metasurface unit model has a reconfigurable range of 4-12 GHz in the C and X bands; the reflection phase change range of the metasurface unit model with the change of the liquid metal size is ≥180°, the iteration can be stopped to obtain the final metasurface reflection unit model.

[0077] The present invention replaces the fixed metal array of the conventional metasurface structure by adopting a microchannel array composed of liquid metal and a plurality of semicircular cross-arm unit microchannel structures, and by setting a drive control unit with the same number of subarray structures as in the liquid metal microchannel structure, each drive control unit is set one-to-one with each subarray structure, and each drive control unit independently controls the flow position and shape of the liquid metal in the corresponding subarray microchannel, and by controlling the continuous adjustability of the liquid metal in the semicircular cross-arm flow channel, the resonant frequency and reflection phase of the reflection unit are continuously reconfigurable, and the conventional metasurface unit uses PIN diodes and other components to adjust the electromagnetic response state. The problems such as limited control state and insufficient continuous adjustment ability are solved. The liquid metal microchannel structure of the present invention is applied to the reconfigurable metasurface reflection unit, and the liquid metal size adjustment range is increased by bending the flow channel of the cross-shaped structure, and the reflection phase adjustment range is expanded. It has the functions of polarization insensitivity, incident angle insensitivity, continuous adjustment of electromagnetic response, and continuous adjustment of reflection phase over a wide range, and can be applied to radar camouflage stealth, dynamic reconfigurable communication and other fields.

[0078] Example 1

[0079] This embodiment provides a liquid metal microfluidic channel structure, such as Figure 2 , Figure 3 and Figure 5As shown, the unit microfluidic channel structure is a curved cross-shaped structure, including a liquid reservoir 21 and four semicircular cross-arm flow channels, the four semicircular cross arms include a first semicircular cross-arm flow channel 22, a second semicircular cross-arm flow channel 23, a third semicircular cross-arm flow channel 24 and a fourth semicircular cross-arm flow channel 25, the liquid reservoir 21 is located in the center of the microfluidic channel structure, the four semicircular cross-arm flow channels are arranged around the liquid reservoir 21, and are interconnected through the liquid reservoir 21, the four semicircular cross-arm flow channels all extend in a direction away from the liquid reservoir 21, the first semicircular cross-arm flow channel 22 and the third semicircular cross-arm flow channel 25 are connected, and the liquid reservoir 21 is located in the center of the microfluidic channel structure, and the four semicircular cross-arm flow channels are arranged around the liquid reservoir 21, and are interconnected through the liquid reservoir 21, and the four semicircular cross-arm flow channels all extend in a direction away from the liquid reservoir 21. The arc-shaped cross arm flow channel 24 is symmetrically distributed at the center, the second semi-circular arc cross arm flow channel 23 and the fourth semi-circular arc cross arm flow channel 25 are symmetrically distributed at the center, the angle between the first semi-circular arc cross arm flow channel 22 and the second semi-circular arc cross arm flow channel 23 is 90°, the angle between the second semi-circular arc cross arm flow channel 23 and the third semi-circular arc cross arm flow channel 24 is 90°, the angle between the third semi-circular arc cross arm flow channel 24 and the fourth semi-circular arc cross arm flow channel 25 is 90°, and the angle between the fourth semi-circular arc cross arm flow channel 25 and the first circular arc cross arm flow channel 22 is 90°.

[0080] The liquid metal microfluidic channel structure may be arranged on the flexible substrate 4, and the liquid metal microfluidic channel structure is an array structure, and the array structure includes a plurality of periodically arranged sub-array structures, and the sub-array structure includes 3*3 unit microfluidic channel structures;

[0081] The sub-array structures are independent and not connected;

[0082] The sub-array structure includes a plurality of unit microfluidic channel structures, and the plurality of unit microfluidic channel structures are connected through through holes;

[0083] The arrangement period of the unit microfluidic channel structure is P, where P is 15 mm;

[0084] The arrangement period of the sub-array structure is Px, d is the bonding width, where Px is 51 mm, satisfying: NP<Px≤(N+1)P.

[0085] Example 2

[0086] The liquid metal reconfigurable metasurface reflection unit of this embodiment includes the liquid metal microchannel structure provided in Embodiment 1, such as Figures 1 to 4 As shown, it includes: a flexible substrate 4, a flexible film 5, a flexible upper cover plate 6, a drive control structure 8 and a ground plate 9;

[0087] The flexible upper cover plate 6, the flexible film 5, the flexible substrate 4, the ground plate 9 and the drive control structure 8 are stacked in sequence;

[0088] like Figure 3 As shown, the liquid metal microfluidic channel structure is arranged on a flexible substrate 4, and the liquid metal microfluidic channel structure is an array structure, and the array structure includes a plurality of periodically arranged sub-array structures, and the sub-array structure includes 3*3 unit microfluidic channel structures;

[0089] The arrangement period of the unit microfluidic channel structure is P, where P is 15 mm;

[0090] The arrangement period of the sub-array structure is Px, d is the bonding width, where Px is 51 mm, satisfying: NP<Px≤(N+1)P;

[0091] The sub-array structures are independent and not connected;

[0092] The subarray structure includes a plurality of unit microfluidic channel structures, wherein the plurality of unit microfluidic channel structures are connected by through holes, and the unit microfluidic channel structure is a curved cross-shaped structure, including a liquid reservoir 21 and four semicircular cross-arm flow channels, wherein the four semicircular cross arms include a first semicircular cross-arm flow channel 22, a second semicircular cross-arm flow channel 23, a third semicircular cross-arm flow channel 24, and a fourth semicircular cross-arm flow channel 25, wherein the liquid reservoir 21 is located in the center of the microfluidic channel structure, and the four semicircular cross-arm flow channels are arranged around the liquid reservoir 21, and are interconnected through the liquid reservoir 21, and the four semicircular cross-arm flow channels all extend in a direction away from the liquid reservoir 21, and the first The semicircular cross arm channel 22 and the third semicircular cross arm channel 24 are centrally symmetrically distributed, the second semicircular cross arm channel 23 and the fourth semicircular cross arm channel 25 are centrally symmetrically distributed, the angle between the first semicircular cross arm channel 22 and the second semicircular cross arm channel 23 is 90°, the angle between the second semicircular cross arm channel 23 and the third semicircular cross arm channel 24 is 90°, the angle between the third semicircular cross arm channel 24 and the fourth semicircular cross arm channel 25 is 90°, and the angle between the fourth semicircular cross arm channel 25 and the first circular cross arm channel 22 is 90°.

[0093] The flexible film 5 is bonded to the flexible substrate 4 by heat pressing, the flexible upper cover plate 6 is bonded to the flexible film 5 by spraying glue, and the flexible upper cover plate 6 is provided with an air cavity structure 7 which is the same as the unit microchannel structure;

[0094] The driving control structure 8 includes driving control units having the same number as the sub-array structures in the liquid metal microfluidic channel structure, each driving control unit is arranged in a one-to-one correspondence with each sub-array structure, and each driving control unit independently controls the flow position and shape of the liquid metal in the corresponding sub-array microfluidic channel;

[0095] The flexible substrate 4 is provided with the same number of injection ports as the sub-array structures in the liquid metal microfluidic channel structure, each injection port is provided in a one-to-one correspondence with each sub-array structure, and the driving control unit is connected to the injection port on the flexible substrate 4 through an external conduit;

[0096] The ground plate 9 is glued to the flexible substrate 4 and the driving control structure 8 respectively.

[0097] Specifically, the flexible substrate 4, the flexible film 5, and the flexible upper cover plate 6 together form a flexible packaging structure, the thickness h1 of the flexible substrate 4 is 4 mm, the thickness of the flexible film 5 is 40 μm, and the thickness h2 of the flexible upper cover plate 6 is 2 mm;

[0098] The height t2 of the air cavity structure 7 is 1 mm;

[0099] The specific parameters of the liquid metal microfluidic channel structure are: the unit microfluidic channel structure arrangement period P is 15 mm, the semicircular cross arm channel width w1 is 0.5 mm, the arc radius r1 of the semicircular cross arm channel is 3.2 mm, the liquid reservoir width l1 is 2 mm, and the height t1 of the liquid metal microfluidic channel structure is 0.2 mm;

[0100] The materials of the flexible substrate 4, the flexible film 5 and the flexible upper cover plate 6 are SEBS rubber;

[0101] The liquid metal is a gallium-indium-tin alloy;

[0102] Driving liquid: NaOH solution;

[0103] The material of the ground plate 9 is aluminum;

[0104] like Figure 5 The figure shows the liquid metal flow diagram of the metasurface reflection unit of the present embodiment. It can be seen from the figure that the liquid metal 1 is distributed in the liquid storage tank 21 and the four semicircular cross-arm flow channels connected to the liquid storage tank, and the NaOH driving liquid is distributed at the ends of the four semicircular cross-arm flow channels; under the pressure drive of each driving control unit, the driving liquid 3 drives the liquid metal 1 to flow continuously in multiple unit microfluidic channel structures of the sub-array microfluidic channel, and the NaOH driving liquid drives the liquid metal 1 to flow continuously in the microfluidic channel structure, and changes at different flow positions and shapes in the four semicircular cross-arm flow channels of the unit microfluidic channel structure, thereby reconstructing the structural morphology of the liquid metal 1. Each change in the flow position and shape of the liquid metal 1 in the microfluidic channel structure corresponds to a working state of the metasurface, so as to realize dynamic adjustment of the metasurface performance under multiple states. The size change of the liquid metal 1 in the semicircular cross-arm flow channel can be characterized by an angle J, and its adjustment range is 30°<J<180°.

[0105] Figure 6This is a frequency dynamic reconfiguration diagram of the metasurface reflection unit of this embodiment. It can be seen that as the liquid metal flows in the microchannel, the resonant frequency of the metasurface reflection unit can be reconfigured within the range of 4.5 to 12 GHz.

[0106] Figure 7 This is a reflection phase range diagram of the metasurface reflection unit of this embodiment. It can be seen that within the C and X bands, the reflection phase control range of the metasurface reflection unit satisfies 180°.

[0107] Fig.12 This is a reflection phase range diagram of the metasurface reflection unit of this embodiment at the center frequency (f0=8GHz) under X and Y polarizations. It can be seen that the unit has polarization insensitivity.

[0108] Fig.13 3 is a reflection phase range diagram of the metasurface reflection unit of this embodiment at the center frequency (f0=8GHz) under different incident angles. It can be seen that the unit has the characteristic of being insensitive to the incident angle.

[0109] Example 3

[0110] This embodiment provides a method for manufacturing the liquid metal reconfigurable metasurface reflection unit of embodiment 2, comprising the following steps:

[0111] S1: According to the requirements of polarization insensitivity and incident angle insensitivity of the metasurface reflection unit, combined with the fluidic characteristics of liquid metal, the shape and initial size of the unit microfluidic channel structure are designed. The unit microfluidic channel structure is a semicircular cross arm structure;

[0112] Among them, the initial dimensions of the unit microchannel structure are: semicircular cross arm channel width w1 = 0.1 mm, semicircular cross arm radius r1 = 2.5 mm, and liquid reservoir width l1 = 1.4 mm;

[0113] S2: According to the shape, initial size and initial arrangement period of the unit microfluidic structure, the subarray microfluidic structure and the liquid metal microfluidic structure are designed. According to the liquid metal microfluidic structure, the shape and initial size of the flexible substrate and the flexible upper cover are designed;

[0114] The initial arrangement period P of the unit microfluidic channel structure is 12 mm, the sub-array microfluidic channel structure includes 3*3 unit microfluidic channel structures, and the initial arrangement period Px of the sub-array microfluidic channel structure is 42 mm.

[0115] The height of the liquid metal microfluidic channel structure is t1=0.4 mm, the flexible substrate and the flexible upper cover plate are rectangular parallelepiped structures, the thickness of the flexible substrate is h1 is 2 mm, the thickness of the flexible upper cover plate 6 is h2 is 1.4 mm, the air cavity 7 in the flexible upper cover plate 6 has the same shape as the unit microfluidic channel structure, and the height of the air cavity is t2=0.6 mm;

[0116] S3: Input the shape, initial size and initial arrangement period of the unit microfluidic structure, the shape and initial size of the flexible substrate and the flexible upper cover, and the initial size of the flexible film into the CST electromagnetic simulation software to obtain the initial metasurface reflection unit model;

[0117] Among them, the initial thickness of the flexible film is 8 μm;

[0118] S4: Input the material parameters of the flexible substrate, liquid metal and driving liquid, and use CST electromagnetic simulation software to perform multiple parameter sweep iterations on the initial metasurface reflection unit until the iteration stop condition is met to obtain the final metasurface reflection unit model. The dimensions of the unit microfluidic structure, flexible substrate and flexible upper cover plate in the final metasurface reflection unit model are the final dimensions;

[0119] After multiple iterations, the resonant frequency of the final metasurface unit model is reconfigurable within the C and X bands to 4.5-12 GHz; the reflection phase of the final metasurface unit model changes by 180° as the size of the liquid metal changes;

[0120] At this time, in the final supersurface unit model, the specific parameters of the microfluidic array structure are: the unit microfluidic structure arrangement period P is 15 mm, the sub-array microfluidic structure includes 3*3 unit microfluidic structures, and the initial arrangement period Px of the sub-array microfluidic structure is 51 mm;

[0121] The width w1 of the semicircular cross-arm flow channel is 0.5 mm, the arc radius r1 of the semicircular cross-arm flow channel is 3.2 mm, the width l1 of the liquid reservoir is 2 mm, and the height t1 of the liquid metal microfluidic channel structure is 0.2 mm;

[0122] The thickness h1 of the flexible substrate 4 is 4 mm, the thickness of the flexible film 5 is 40 μm, and the thickness h2 of the flexible upper cover plate 6 is 2 mm;

[0123] The height t2 of the air cavity structure 7 is 1 mm.

[0124] S5: According to the final metasurface reflection unit model, a unit microfluidic structure, a flexible substrate and a flexible upper cover plate that meet the shape and size requirements are manufactured;

[0125] S6: According to the final metasurface reflection unit model, a liquid metal microfluidic structure and a liquid injection port are manufactured on a flexible substrate. The microfluidic array structure includes a plurality of sub-array microfluidic structures. Each sub-array microfluidic structure includes 3*3 unit microfluidic structures. Each unit microfluidic structure in the sub-array is connected by a through hole. The sub-array microfluidic structures are independent of each other and are not connected.

[0126] S7: Based on the final metasurface reflective unit model, a flexible film is bonded on a flexible substrate using a hot pressing method;

[0127] S8: According to the final metasurface reflection unit model, an air cavity structure with the same shape as the unit microfluidic channel structure is manufactured in the flexible upper cover plate, and the height of the air cavity structure is greater than the height of the microfluidic channel array structure;

[0128] S9: injecting a driving liquid through the injection port, and injecting the driving liquid into the flow channel of each unit microfluidic channel structure through the through holes between the unit microfluidic channel structures;

[0129] S10: injecting liquid metal through the injection port, and the liquid metal is injected into the flow channel of each unit microfluidic channel structure through the through holes between the unit microfluidic channel structures;

[0130] S11: bonding the flexible upper cover plate to the flexible film by spraying glue;

[0131] S12: Disposing a ground plate under the flexible substrate;

[0132] S13: Drive control units having the same number as the sub-array microfluidic channels are arranged under the ground plane to form a drive control structure, and each drive control unit is connected to a corresponding injection port to obtain a metasurface reflection unit entity.

[0133] Comparative Example

[0134] The metasurface reflection unit of this comparative example includes: a flexible substrate, a flexible film, a flexible upper cover plate, a driving control structure and a ground plate;

[0135] The flexible upper cover plate, the flexible film, the flexible substrate, the ground plate and the drive control structure are stacked in sequence;

[0136] The flexible substrate is provided with a microfluidic array structure and a liquid injection port, wherein the microfluidic array structure includes a plurality of unit microfluidic structures, wherein the plurality of unit microfluidic structures are connected by through holes, wherein the unit microfluidic structure is a vertical cross-shaped structure, including a liquid reservoir and four mutually perpendicular rectangular cross-arm flow channels, wherein the liquid reservoir is located in the center of the microfluidic structure, and the four mutually perpendicular rectangular cross-arm flow channels are arranged around the liquid reservoir; the unit microfluidic structure is as follows Figure 7 As shown;

[0137] The flexible film is bonded to the flexible substrate by heat pressing, the flexible upper cover is bonded to the flexible film by spraying glue, and an air cavity structure having the same structure as the microchannel structure is manufactured in the flexible upper cover;

[0138] The driving control structure is connected to the liquid injection port on the flexible substrate;

[0139] The ground plate is glued to the flexible substrate and the driving control structure respectively.

[0140] Specifically, the flexible substrate, the flexible film, and the flexible upper cover plate together form a flexible packaging structure, the thickness h1 of the flexible substrate is 4 mm, the thickness of the flexible film is 40 μm, and the thickness h2 of the flexible upper cover plate is 2 mm;

[0141] The height t2 of the air cavity structure is 1 mm;

[0142] The specific parameters of the microfluidic array structure are: unit microfluidic structure arrangement period P = 15mm, rectangular cross arm channel width w1 = 0.2mm, channel length l2 = 5.9mm, liquid reservoir width l1 = 2mm, microfluidic array height t1 is 0.2mm; liquid metal flow control angle 0mm<l0<6mm.

[0143] The materials of the flexible substrate 4, the flexible film 5 and the flexible upper cover plate 6 are SEBS rubber;

[0144] The liquid metal is a gallium-indium-tin alloy;

[0145] Driving liquid: NaOH solution;

[0146] The material of the ground plate 9 is aluminum.

[0147] Fig. 9 This is the frequency dynamic reconfiguration diagram of the metasurface reflection unit in this comparative example. It can be seen that as the liquid metal flows in the microchannel, the resonant frequency of the unit can be reconfigured within the range of 6 to 12 GHz. Fig.10 This is the reflection phase range diagram of the comparison metasurface reflection unit. It can be seen that in the 6-12 GHz band, the reflection phase control range of the unit satisfies 180°.

[0148] By comparison, it can be seen that the resonant frequency of the metasurface reflection unit in Example 2 or Example 3 of the present invention can be reconfigured within the range of 4.5 to 12 GHz as the liquid metal flows in the microchannel; the resonant frequency of the metasurface reflection unit in the comparative example can be reconfigured within the range of 6 to 12 GHz as the liquid metal flows in the microchannel; the reconfigurable range of the metasurface reflection unit in Example 2 or Example 3 of the present invention is slightly wider than that of the comparative example. Fig.11 It can be seen that the reflection phase control range of the metasurface reflection unit in Example 2 or Example 3 of the present invention is wider than that of the comparative example.

[0149] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A liquid metal microfluidic channel structure, characterized in that: It comprises a plurality of unit microfluidic channel structures, wherein the unit microfluidic channel structure is a bent cross-shaped structure, comprising a liquid storage tank and four semicircular cross-arm flow channels.

2. The liquid metal microfluidic channel structure according to claim 1, characterized in that: The liquid metal microfluidic channel structure is an array structure, and the array structure includes a plurality of periodically arranged sub-array structures, and the sub-array structure includes N*N unit microfluidic channel structures, where 3≤N≤5.

3. The liquid metal microfluidic channel structure according to claim 2, characterized in that: The unit microchannel structures are interconnected, and the sub-array structures are independent of each other and not interconnected.

4. The liquid metal microfluidic channel structure according to claim 1, characterized in that: The arrangement period of the unit microfluidic channel structure is P, wherein P is 13-17 mm.

5. The liquid metal microfluidic channel structure according to claim 4, characterized in that: The arrangement period of the sub-array structure is P x , where P x Satisfies: NP<Px≤(N+1)P.

6. The liquid metal microfluidic channel structure according to claim 1, characterized in that: The liquid reservoir is located in the center of the microchannel structure. The four semicircular cross-arm flow channels are arranged around the liquid reservoir and are interconnected through the liquid reservoir. The four semicircular cross-arm flow channels all extend in a direction away from the liquid reservoir.

7. The liquid metal microfluidic channel structure according to claim 6, characterized in that: The four semicircular cross-arm flow channels include a first semicircular cross-arm flow channel, a second semicircular cross-arm flow channel, a third semicircular cross-arm flow channel and a fourth semicircular cross-arm flow channel; The first semicircular arc cross arm flow channel and the third semicircular arc cross arm flow channel are centrally symmetrically distributed, and the second semicircular arc cross arm flow channel and the fourth semicircular arc cross arm flow channel are centrally symmetrically distributed.

8. The liquid metal microfluidic channel structure according to claim 7, characterized in that: The angle between the first semicircular arc cross arm flow channel and the second semicircular arc cross arm flow channel is 90°, the angle between the second semicircular arc cross arm flow channel and the third semicircular arc cross arm flow channel is 90°, the angle between the third semicircular arc cross arm flow channel and the fourth semicircular arc cross arm flow channel is 90°, and the angle between the fourth semicircular arc cross arm flow channel and the first circular arc cross arm flow channel is 90°.

9. The liquid metal microfluidic channel structure according to claim 1, characterized in that: The width w1 of the semicircular cross-arm flow channel is 0.2-0.6 mm, the arc radius r1 of the semicircular cross-arm flow channel is 3-3.5 mm, and the width l1 of the liquid storage tank is 1.5-2.5 mm.

10. A liquid metal reconfigurable metasurface reflection unit, characterized in that: The liquid metal reconfigurable metasurface unit comprises the liquid metal microfluidic structure described in any one of claims 1-9.

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