Liquid metal micro-channel structure and reconfigurable metasurface reflection unit

Abstract

The present application relates to a kind of liquid metal microchannel structure and reconfigurable metasurface reflection unit, belong to artificial electromagnetic material technical field.The existing microchannel structure is applied to metasurface reflection unit, and the problems of discrete limited regulation state, insufficient continuous adjustment capability, narrow adjustment bandwidth, small reflection phase shift range are solved.A kind of liquid metal microchannel structure, including multiple unit microchannel structures, unit microchannel structure is curved cross-shaped structure, including liquid pool and four semicircular arc cross arm flow channel.The present application is by using liquid metal and the microchannel array of multiple semicircular arc cross arm type unit microchannel structure instead of the fixed metal array of conventional metasurface structure, by controlling the continuous adjustable of liquid metal in semicircular arc cross arm flow channel, realizes the continuous reconfigurable of metasurface reflection unit structure, with polarization insensitive, incident angle insensitive, reflection phase shift range large characteristics.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of artificial electromagnetic materials, and particularly relates to a liquid metal micro-channel structure and a reconfigurable metasurface reflection unit. BACKGROUND

[0002] Liquid metal is a conductive metal that can flow at room temperature, and it combines the excellent properties of traditional rigid and flexible materials. In recent years, with the continuous development of liquid metal technology, different alloy materials can be used to achieve different viscosity, melting point, conductivity and other performance characteristics. By integrating the large deformation and flow of liquid metal with microstructures, the filling and micro-flow of liquid metal in the micro-channel structure can be achieved, which has the characteristics of flexibility, low cost and reconfigurability. Therefore, liquid metal technology has become a promising new technology and can be widely used in flexible electronics, flexible sensing, reconfigurable antennas, metamaterials and other fields.

[0003] By using the arbitrary flowability of liquid metal, the liquid metal can flow in the micro-channel encapsulation structure, which can replace the role of solid metal in the metasurface structure. By controlling the flow of liquid metal in the flow channel, the continuous reconfiguration of electromagnetic response state can be realized. In order to realize the distribution form of liquid metal in the flow channel structure, it is necessary to drive and control the precise flow characteristics of liquid metal in the flow channel structure. However, the application of liquid metal in the micro-channel structure is still in its infancy, and there are few reports on the influence of the shape of liquid metal in the micro-channel structure on the performance of the metasurface. The existing micro-channel structure has a small size adjustment range of liquid metal and a small reflection phase adjustment range. SUMMARY

[0004] In view of the above analysis, the embodiments of the present application aim to provide a liquid metal micro-channel structure and a reconfigurable metasurface reflection unit to solve at least one of the following problems of the existing liquid metal micro-channel and metasurface reflection unit structure: 1. The existing micro-channel structure is applied to the reconfigurable metasurface reflection unit, and the discrete control state is limited; 2. The existing micro-channel 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 micro-channel structure is applied to the reconfigurable metasurface reflection unit, and the reflection phase shift range is small.

[0005] The purpose of the present application is mainly realized by the following technical solutions:

[0006] On the one hand, the present application provides a liquid metal micro-channel structure, which comprises a plurality of unit micro-channel structures, wherein the unit micro-channel structure is a curved cross-shaped structure comprising a liquid storage pool and four semi-circular arc cross-arm flow channels.

[0007] Further, the liquid metal micro-channel structure is an array structure, the array structure comprises a plurality of periodically arranged sub-array structures, the sub-array structure comprises N*N unit micro-channel structures, and 3≤N≤5.

[0008] Further, the unit micro-channel structures are mutually penetrated, and the sub-array structures are independent and not connected.

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

[0010] Further, the arrangement period of the sub-array structure is Px, wherein Px satisfies NP

[0011] Further, the liquid pool is located at the center of the micro-channel structure, the four semi-circular arc cross arm flow channels are arranged around the liquid pool and are connected to each other through the liquid pool, and the four semi-circular arc cross arm flow channels all extend away from the liquid pool.

[0012] Further, the four semi-circular arc cross arm flow channels comprise a first semi-circular arc cross arm flow channel, a second semi-circular arc cross arm flow channel, a third semi-circular arc cross arm flow channel and a fourth semi-circular arc cross arm flow channel.

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

[0014] Further, the included angle between the first semi-circular arc cross arm flow channel and the second semi-circular arc cross arm flow channel is 90°, the included angle between the second semi-circular arc cross arm flow channel and the third semi-circular arc cross arm flow channel is 90°, the included angle between the third semi-circular arc cross arm flow channel and the fourth semi-circular arc cross arm flow channel is 90°, and the included angle between the fourth semi-circular arc cross arm flow channel and the first semi-circular arc cross arm flow channel is 90°.

[0015] Further, the width w1 of the semi-circular arc cross arm flow channel is 0.2-0.6 mm, the arc radius r1 of the semi-circular arc cross arm flow channel is 3-3.5 mm, and the width l1 of the liquid pool is 1.5-2.5 mm.

[0016] In another aspect, the application also provides a liquid metal reconfigurable metasurface reflection unit comprising the above liquid metal micro-channel structure.

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

[0018] 1. The application provides a liquid metal micro-channel structure, comprising a plurality of unit micro-channel structures, the unit micro-channel structure is a curved cross-shaped structure, comprising a liquid pool and four semi-circular arc-shaped cross arm flow channels, by controlling the continuous adjustment of the liquid metal in the semi-circular arc-shaped cross arm flow channel, the application can solve the problems of small size adjustment range, insufficient continuous adjustment capability and narrow adjustment bandwidth of the existing micro-channel structure liquid metal.

[0019] 2. The application adopts a micro-channel array composed of liquid metal and a plurality of semi-circular arc-shaped cross arm type unit micro-channel structures instead of a fixed metal array of a conventional metasurface structure, sets driving control units same in number as the sub-array structures in the liquid metal micro-channel structure, sets each driving control unit one-to-one corresponding to each sub-array structure, independently controls the flow position and shape of the liquid metal in the corresponding sub-array micro-channel of each driving control unit, controls the continuous adjustment of the liquid metal in the semi-circular arc-shaped cross arm flow channel, realizes the continuous reconfiguration of the resonant frequency and reflection phase of the reflection unit, and solves the problems of limited control state, insufficient continuous adjustment capability and the like faced by the conventional metasurface unit using PIN diode elements to adjust the electromagnetic response state.

[0020] 3. The liquid metal micro-channel structure of the application is applied to a reconfigurable metasurface reflection unit, increases the size adjustment range of the liquid metal through the flow channel of the curved cross-shaped structure, expands the reflection phase adjustment range, has the functions of polarization insensitivity, incident angle insensitivity, continuous adjustable electromagnetic response, large-range continuous adjustable reflection phase, and can be applied to radar camouflage stealth, dynamic reconfigurable communication and other fields.

[0021] In the application, the above technical solutions can be combined with each other to realize more preferred combination solutions. Other features and advantages of the application will be described in the subsequent specification, and some advantages will become apparent from the specification or be understood by implementing the application. The purposes and other advantages of the application can be realized and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings are included to provide a further understanding of the application and are incorporated herein and constitute a part of the application. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0023] Figure 1 The liquid metal and driving liquid distribution diagram in the liquid metal unit micro-channel structure of the embodiment of the application;

[0024] Figure 2 The top view of the liquid metal unit micro-channel structure of the embodiment of the application;

[0025] Figure 3 Top view of liquid metal sub-array micro-channel structure of the embodiment of the present application;

[0026] Figure 4 Sectional view of liquid metal reconfigurable metasurface reflecting unit of the embodiment of the present application;

[0027] Figure 5 Flowing schematic of liquid metal in unit micro-channel structure of the embodiment of the present application;

[0028] Figure 6 Frequency dynamic reconfigurable diagram of liquid metal reflecting unit of the embodiment of the present application;

[0029] Figure 7 Reflection phase range diagram of liquid metal reflecting unit of the embodiment of the present application;

[0030] Figure 8 Top view of unit micro-channel structure of liquid metal reflecting unit of the comparative example;

[0031] Figure 9 Frequency dynamic reconfigurable diagram of liquid metal reflecting unit of the comparative example;

[0032] Figure 10 Reflection phase range diagram of liquid metal reflecting unit of the comparative example;

[0033] Figure 11 Reflection phase range comparison diagram of liquid metal reflecting unit of the embodiment and the comparative example of the present application;

[0034] Figure 12 Reflection phase comparison diagram of liquid metal reflecting unit of the embodiment of the present application under X, Y polarization of center frequency (f 0＝ 8GHz);

[0035] Figure 13 Reflection phase comparison diagram of liquid metal reconfigurable metasurface reflecting unit of the embodiment of the present application under different incident angles of center frequency (f 0＝ 8GHz).

[0036] Reference signs:

[0037] 1-liquid metal; 2-liquid metal micro-channel structure; 21-liquid storage pool; 22-first semicircular arc cross arm flow channel; 23-second semicircular arc cross arm flow channel; 24-third semicircular arc cross arm flow channel; 25-fourth semicircular arc cross arm flow 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 is the arrangement period of the unit microfluid channel structure; Px is the arrangement period of the subarray microfluid channel structure; d is the bonding width between the subarray microfluid channel structures; w1 is the width of the semicircular cross arm channel of the unit microfluid channel structure; r1 is the radius of the semicircular cross arm channel; l1 is the width of the liquid pool; t1 is the height of the liquid metal microfluid channel structure; h1 is the thickness of the flexible substrate; h2 is the thickness of the flexible upper cover plate; t2 is the air cavity structure 7; J is the circular arc angle of the liquid metal flowing in the semicircular cross arm channel of the unit microfluid channel structure. DETAILED DESCRIPTION

[0039] The preferred embodiments of the present application will be described in detail below with reference to the drawings, which form a part of this application, and together with the embodiments of the present application illustrate the principles of the present application, but are not intended to limit the scope of the present application.

[0040] The present application provides a liquid metal microfluid channel structure, comprising a plurality of unit microfluid channel structures, the unit microfluid channel structure is a curved cross structure, comprising a liquid pool and four semicircular cross arm channels.

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

[0042] The liquid metal microfluid channel structure is an array structure, the array structure comprises a plurality of periodically arranged subarray structures, the subarray structure comprises N*N unit microfluid channel structures, wherein 3≤N≤5;

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

[0044] The arrangement period of the subarray structure is Px, wherein Px satisfies NP Figure 3 As shown in the figure, the subarray structure comprises 3*3 unit microfluid channel structures, wherein d is the bonding width between the subarray microfluid channel structures, generally 2-4mm, and Px is 43-59mm.

[0045] The application can replace the fixed metal array of the conventional metasurface structure by adopting a microfluid channel array composed of liquid metal and multiple semicircular arc cross arm type unit microfluid channel structures, set the same number of driving control units as the number of subarray structures in the liquid metal microfluid channel structure, set each driving control unit one by one corresponding to each subarray structure, independently control the flow position and shape of the liquid metal in the corresponding subarray microfluid channel of each driving control unit, continuously and reconfigure the resonant frequency and reflection phase of the reflection unit by continuously adjusting the liquid metal in the semicircular arc cross arm channel, and solve the problems of limited regulation state and insufficient continuous adjustment capability faced by the conventional metasurface unit using PIN diode elements to adjust the electromagnetic response state.

[0046] The unit microfluid channel structures are mutually penetrated and are in a curved cross structure, including a liquid storage pool and four semicircular arc cross arm channels. Figure 1 As shown in the figure, the liquid storage pool 21 is located in the center of the unit microfluid channel structure, the four semicircular arc cross arm channels are arranged around the liquid storage pool and are connected to each other through the liquid storage pool, and the four semicircular arc cross arm channels all extend away from the liquid storage pool; the four semicircular arc cross arm channels include a first semicircular arc cross arm channel 22, a second semicircular arc cross arm channel 23, a third semicircular arc cross arm channel 24 and a fourth semicircular arc cross arm channel 25; the first semicircular arc cross arm channel 22 and the third semicircular arc cross arm channel 24 are centrally symmetrically distributed, and the second semicircular arc cross arm channel 23 and the fourth semicircular arc cross arm channel 25 are centrally symmetrically distributed; the included angle between the first semicircular arc cross arm channel 22 and the second semicircular arc cross arm channel 23 is 90°, the included angle between the second semicircular arc cross arm channel 23 and the third semicircular arc cross arm channel 24 is 90°, the included angle between the third semicircular arc cross arm channel 24 and the fourth semicircular arc cross arm channel 25 is 90°, and the included angle between the fourth semicircular arc cross arm channel 25 and the first semicircular arc cross arm channel 22 is 90°.

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

[0048] The liquid metal microfluid channel structure of the application is applied to a reconfigurable metasurface reflection unit, increases the size adjustment range of the liquid metal through the channel of the curved cross structure, expands the reflection phase adjustment range, has the functions of polarization insensitivity, incident angle insensitivity, continuous adjustable electromagnetic response, large-range continuous adjustable reflection phase and the like, and can be applied to the fields of radar camouflage stealth, dynamic reconfigurable communication and the like.

[0049] Based on this, the application further provides a liquid metal reconfigurable metasurface reflection unit, comprising the liquid metal micro-channel structure.

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

[0051] The flexible upper cover plate 6, the flexible film 5, the flexible substrate 4, the grounding plate 9 and the driving control structure 8 are sequentially stacked.

[0052] The liquid metal micro-channel structure is arranged on the flexible substrate 4, the flexible film 5 is adhered on the flexible substrate 4 by hot pressing, the flexible upper cover plate 6 is adhered on the flexible film 5 by spraying glue, and the same air cavity structure 7 as the unit micro-channel structure is arranged in the flexible upper cover plate 6.

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

[0054] The same number of liquid injection ports as the number of sub-array structures in the liquid metal micro-channel structure is arranged on the flexible substrate 4, each liquid injection port is arranged in one-to-one correspondence with each sub-array structure, and the driving control unit is connected with the liquid injection port on the flexible substrate 4 through an external connecting pipe, for controlling the flow state of the liquid metal in the plurality of unit micro-channel structures, such as position and shape.

[0055] The grounding plate 9 is glued on both sides of the flexible substrate 4 and the driving control structure 8.

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

[0057] Specifically, the flexible film 5 is adhered on the flexible substrate by hot pressing, so as to seal the liquid metal 1 and the driving liquid 3 and avoid liquid leakage.

[0058] Specifically, the air cavity structure 7 with the same structure as the unit micro-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 micro-channel array structure, so as to accommodate the volume change of the liquid in the plurality of unit micro-channel structures.

[0059] It should be noted that the liquid metal micro-channel structure 2 is arranged on the flexible substrate 4, as shown in Figure 1 and Figure 4 The liquid metal 1 is distributed in the liquid pool 21 and the four semi-circular arc cross arm flow channels connected to the liquid pool, and the driving liquid is distributed at the end of the four semi-circular arc cross arm flow channels; under the pressure driving of the respective driving control unit, the driving liquid 3 pushes the liquid metal 1 to flow continuously in the multiple unit micro-channel structures, and changes in different flow positions and shapes in the four semi-circular arc cross arm flow channels of the multiple unit micro-channel structures, thereby reconstructing the structural morphology of the liquid metal 1. The flow position and shape of the liquid metal 1 in the micro-channel structure change each time, corresponding to one working state of the metasurface, so as to realize dynamic adjustment of the performance of the metasurface in multiple states. The size of the liquid metal changes in the range of 30°<J<180° when it flows in the semi-circular arc cross arm flow channel of the liquid metal reconfigurable metasurface reflection unit, where J is the arc angle of the liquid metal when it flows in the semi-circular arc cross arm flow channel (as shown in Figure 1 The change in size and shape of the liquid metal changes its resonant structure, thereby causing changes in its response frequency, reflection phase and working state, and realizing dynamic reconfiguration of the resonant frequency in the C and X bands, and continuous dynamic adjustment of the reflection phase.

[0060] The liquid metal micro-channel structure 2 is prepared on the flexible substrate 4, and the relative dielectric constant, loss tangent, and conductivity material parameters of the flexible substrate, the liquid metal, and the driving liquid are used to design the unit resonant structure and its size parameters of the unit micro-channel structure. To increase the adjustment range of the unit reflection phase of the metasurface, the unit resonant structure is designed as a semi-circular arc cross arm structure, which increases the adjustment range of the liquid metal resonant part and widens the adjustment range of the reflection phase. According to the unit resonant structure and the flow mode of the liquid metal, a square liquid pool is designed at the center connection of the semi-circular arc cross arm flow channel structure to facilitate the storage of liquid when the driving liquid is injected. The unit micro-channel structure is realized by micro-nano processing technology, including photolithography, nano-imprinting and other process methods.

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

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

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

[0064] Optionally, the material of the ground plate 9 is metal for reflecting electromagnetic waves, and aluminum, copper or the like can be used.

[0065] The application further provides a manufacturing method of the liquid metal reconfigurable metasurface reflecting unit.

[0066] S1: determining the shape and initial size of the unit micro-channel structure, the unit micro-channel structure being a semicircular arc type cross arm structure;

[0067] S2: designing the subarray micro-channel structure and the liquid metal micro-channel structure according to the shape, initial size and initial arrangement period of the unit micro-channel structure, and designing the shape and initial size of the flexible base and the flexible upper cover plate according to the liquid metal micro-channel structure;

[0068] S3: inputting the shape, initial size and initial arrangement period of the unit micro-channel structure, the shape and initial size of the flexible base and the flexible upper cover plate, and the initial size of the flexible film into electromagnetic simulation software to obtain an initial metasurface reflecting unit model;

[0069] S4: inputting the material parameters of the flexible base, the liquid metal and the driving liquid, and using the electromagnetic simulation software to perform multiple parameter scanning iterations on the initial metasurface reflecting unit model to obtain a final metasurface reflecting unit model, and determining that the sizes of the unit micro-channel structure, the flexible base, the flexible film and the flexible upper cover plate in the final metasurface reflecting unit model are final sizes;

[0070] S5: manufacturing the unit micro-channel structure, the flexible base and the flexible upper cover plate with the required shape and size according to the final metasurface reflecting unit model;

[0071] S6: manufacturing the liquid metal micro-channel structure and the liquid injection port on the flexible base;

[0072] S7: bonding the flexible film on the flexible base by using the hot pressing method according to the final metasurface reflecting unit model, and opening an air cavity structure with the same shape as the unit micro-channel structure in the flexible upper cover plate;

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

[0074] S9: the flexible upper cover plate is adhered on the flexible film by spraying glue; a grounding plate is arranged under the flexible substrate; a driving control unit same in number as the subarray microfluid channel is arranged under the grounding plate to form a driving control structure, each driving control unit is connected with a corresponding liquid injection port, and a super surface reflection unit is obtained.

[0075] Specifically, in step S1, according to the requirements of polarization insensitivity and incident angle insensitivity of the super surface reflection unit, and in combination with the flow control characteristics of the liquid metal, the shape and initial size of the unit microfluid channel structure are designed.

[0076] Specifically, in step S4, the material parameters of the flexible substrate, the liquid metal and the driving liquid include the relative dielectric constant, the loss tangent and the conductivity of the material; when the super surface reflection unit model meets the following conditions at the same time: the reconfigurable range of the resonance frequency of the super surface unit model in the C and X wave bands is 4-12 GHz; and the reflection phase change range of the super surface unit model with the size change of the liquid metal is greater than or equal to 180°, the iteration is stopped, and the final super surface reflection unit model is obtained.

[0077] The liquid metal microfluid channel structure of the application is applied to a reconfigurable super surface reflection unit, the size adjustment range of the liquid metal is increased by the curved cross-shaped flow channel, the reflection phase adjustment range is expanded, the functions of polarization insensitivity, incident angle insensitivity, continuous adjustable electromagnetic response and large-range continuous adjustable reflection phase are achieved, and the liquid metal microfluid channel structure can be applied to radar camouflage stealth, dynamic reconfigurable communication and other fields.

[0078] Embodiment 1

[0079] The embodiment provides a liquid metal microfluid channel structure, as shown in Figure 2 、 Figure 3 and Figure 5As shown in the figure, the unit microfluid channel structure is a curved cross structure, including a liquid pool 21 and four semi-circular cross arm flow channels, the four semi-circular cross arm flow channels including a first semi-circular cross arm flow channel 22, a second semi-circular cross arm flow channel 23, a third semi-circular cross arm flow channel 24 and a fourth semi-circular cross arm flow channel 25, the liquid pool 21 is located in the center of the microfluid channel structure, the four semi-circular cross arm flow channels are arranged around the liquid pool 21 and are in communication with each other through the liquid pool 21, the four semi-circular cross arm flow channels all extend away from the liquid pool 21, the first semi-circular cross arm flow channel 22 and the third semi-circular cross arm flow channel 24 are symmetrically distributed at the center, the second semi-circular cross arm flow channel 23 and the fourth semi-circular cross arm flow channel 25 are symmetrically distributed at the center, the included angle between the first semi-circular cross arm flow channel 22 and the second semi-circular cross arm flow channel 23 is 90°, the included angle between the second semi-circular cross arm flow channel 23 and the third semi-circular cross arm flow channel 24 is 90°, the included angle between the third semi-circular cross arm flow channel 24 and the fourth semi-circular cross arm flow channel 25 is 90°, and the included angle between the fourth semi-circular cross arm flow channel 25 and the first semi-circular cross arm flow channel 22 is 90°.

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

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

[0082] The sub-array structure includes a plurality of unit microfluid channel structures, and the plurality of unit microfluid channel structures are penetrated by a through hole;

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

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

[0085] Embodiment 2

[0086] The liquid metal reconfigurable metasurface reflecting unit of the embodiment includes the liquid metal microfluid channel structure provided in embodiment 1, as shown in the figure, and includes a flexible substrate 4, a flexible film 5, a flexible upper cover plate 6, a driving control structure 8 and a grounding plate 9; Figures 1 to 4

[0087] The flexible upper cover plate 6, the flexible film 5, the flexible substrate 4, the grounding plate 9 and the driving control structure 8 are sequentially laminated;

[0088] As shown in the figure, the liquid metal reconfigurable metasurface reflecting unit includes a flexible substrate 4, a flexible film 5, a flexible upper cover plate 6, a driving control structure 8 and a grounding plate 9;​Figure 3 As shown, the liquid metal micro-channel structure is arranged on the flexible substrate 4, the liquid metal micro-channel structure is an array structure, the array structure includes a plurality of periodically arranged sub-array structures, and the sub-array structure includes 3*3 unit micro-channel structures;

[0089] The arrangement period of the unit micro-channel structure is P, wherein P is 15 mm;

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

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

[0092] The sub-array structure includes a plurality of unit micro-channel structures, the plurality of unit micro-channel structures are penetrated through by a through hole, the unit micro-channel structure is a curved cross-shaped structure, includes a liquid pool 21 and four semi-circular arc type cross arm flow channels, the four semi-circular arc type cross arm flow channels include a first semi-circular arc type cross arm flow channel 22, a second semi-circular arc type cross arm flow channel 23, a third semi-circular arc type cross arm flow channel 24 and a fourth semi-circular arc type cross arm flow channel 25, the liquid pool 21 is located in the center of the micro-channel structure, the four semi-circular arc type cross arm flow channels are arranged around the liquid pool 21 and are connected to each other through the liquid pool 21, the four semi-circular arc type cross arm flow channels all extend away from the liquid pool 21, the first semi-circular arc type cross arm flow channel 22 and the third semi-circular arc type cross arm flow channel 24 are centrally symmetrically distributed, the second semi-circular arc type cross arm flow channel 23 and the fourth semi-circular arc type cross arm flow channel 25 are centrally symmetrically distributed, the included angle between the first semi-circular arc type cross arm flow channel 22 and the second semi-circular arc type cross arm flow channel 23 is 90°, the included angle between the second semi-circular arc type cross arm flow channel 23 and the third semi-circular arc type cross arm flow channel 24 is 90°, the included angle between the third semi-circular arc type cross arm flow channel 24 and the fourth semi-circular arc type cross arm flow channel 25 is 90°, and the included angle between the fourth semi-circular arc type cross arm flow channel 25 and the first semi-circular arc type cross arm flow channel 22 is 90°.

[0093] The flexible film 5 is bonded on the flexible substrate 4 by hot pressing, the flexible upper cover plate 6 is bonded on 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 micro-channel structure;

[0094] The driving control structure 8 includes a same number of driving control units as the number of sub-array structures in the liquid metal micro-channel structure, each driving control unit is arranged one by one 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 micro-channel;

[0095] The flexible substrate 4 is provided with the same number of injection ports as the sub-array structures in the liquid metal microchannel structure. Each injection port corresponds to each sub-array structure. The drive control unit is connected to the injection ports on the flexible substrate 4 through an external conduit.

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

[0097] Specifically, the flexible substrate 4, the flexible film 5, and the flexible 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 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 microchannel structure are as follows: the arrangement period P of the unit microchannel structure is 15mm, the width w1 of the semi-circular arc cross arm channel is 0.5mm, the arc radius r1 of the semi-circular arc cross arm channel is 3.2mm, the width l1 of the liquid storage pool is 2mm, and the height t1 of the liquid metal microchannel structure is 0.2mm.

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

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

[0102] Driving fluid: NaOH solution;

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

[0104] like Figure 5 The diagram shows the liquid metal flow pattern of the metasurface reflective unit in this embodiment. As can be seen from the diagram, liquid metal 1 is distributed in the storage tank 21 and four semi-circular cross-arm channels connected to the storage tank. NaOH driving liquid is distributed at the ends of the four semi-circular cross-arm channels. Under the pressure drive of their respective driving control units, driving liquid 3 pushes liquid metal 1 to flow continuously in the multiple unit microchannel structures of the sub-array microchannel. NaOH driving liquid pushes liquid metal 1 to flow continuously in the microchannel structure, and changes under different flow positions and shapes in the four semi-circular cross-arm channels of the unit microchannel structure, thereby reconstructing the structural morphology of liquid metal 1. Each change in the flow position and shape of liquid metal 1 in the microchannel structure corresponds to a working state of the metasurface, so as to realize the dynamic adjustment of the metasurface performance under multiple states. The size change of liquid metal 1 in the semi-circular cross-arm channels can be characterized by the angle J, and its adjustment range is 30° < J < 180°.

[0105] Figure 6For the frequency dynamic reconfigurable map of the super surface reflection unit of the present embodiment, it can be known that as the liquid metal flows in the micro channel, the resonance frequency point of the super surface reflection unit can be reconfigured in the range of 4.5-12 GHz.

[0106] Figure 7 For the reflection phase range map of the super surface reflection unit of the present embodiment, it can be known that in the C and X bands, the reflection phase control range of the super surface reflection unit satisfies 180°.

[0107] Figure 12 For the reflection phase range map of the super surface reflection unit of the present embodiment under X and Y polarizations at the center frequency point (f0=8 GHz), it can be known that the unit has polarization-insensitive characteristics.

[0108] Figure 13 For the reflection phase range map of the super surface reflection unit of the present embodiment at different incident angles at the center frequency point (f0=8 GHz), it can be known that the unit has incident angle-insensitive characteristics.

[0109] Embodiment 3

[0110] The present embodiment provides a manufacturing method of the liquid metal reconfigurable super surface reflection unit of embodiment 2, comprising the following steps:

[0111] S1: According to the polarization-insensitive and incident angle-insensitive requirements of the super surface reflection unit, and in combination with the liquid metal flow control characteristics, the shape and initial size of the unit micro channel structure are designed, and the unit micro channel structure is a semicircular arc type cross arm structure;

[0112] Among them, the initial size of the unit micro channel structure is: the semicircular arc type cross arm channel width w1=0.1mm, the semicircular arc type cross arm radius r1=2.5mm, and the liquid pool width l1=1.4mm;

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

[0114] Among them, the initial arrangement period P of the unit micro channel structure is 12mm, the subarray micro channel structure includes 3*3 unit micro channel structures, and the initial arrangement period Px of the subarray micro channel structure is 42mm;

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

[0116] S3: input the shape, initial size and initial arrangement period of the unit microfluid 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 CST electromagnetic simulation software to obtain an initial metasurface reflecting unit model;

[0117] 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 the CST electromagnetic simulation software to perform multiple sweep iteration on the initial metasurface reflecting unit until the iteration stopping condition is met to obtain a final metasurface reflecting unit model, and the sizes of the unit microfluid channel structure, the flexible substrate and the flexible upper cover plate in the final metasurface reflecting unit model are final sizes;

[0119] After multiple iterations, the reconfigurable range of the resonant frequency of the final metasurface unit model in the C and X bands is 4.5-12 GHz; and the change range of the reflection phase of the final metasurface unit model with the size of the liquid metal is 180°.

[0120] At this time, in the final metasurface unit model, the specific parameters of the microfluid channel array structure are: the arrangement period P of the unit microfluid channel structure is 15 mm, the subarray microfluid channel structure includes 3*3 unit microfluid channel structures, and the initial arrangement period Px of the subarray microfluid channel 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 liquid pool width l1 is 2 mm, and the height t1 of the liquid metal microfluid 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 reflecting unit model, the unit microfluid channel structure, the flexible substrate and the flexible upper cover plate meeting the shape and size requirements are manufactured;

[0125] S6: according to the final metasurface reflecting unit model, the liquid metal microfluid channel structure and the liquid injection port are manufactured on the flexible substrate, the microfluid channel array structure includes multiple subarray microfluid channel structures, each subarray microfluid channel structure includes 3*3 unit microfluid channel structures, each unit microfluid channel structure in the subarray is connected through a through hole, and the subarray microfluid channel structures are independent of each other and do not penetrate each other.

[0126] S7: according to the final metasurface reflecting unit model, the flexible film is bonded to the 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 micro-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 micro-channel array structure;

[0128] S9: Inject driving liquid through the liquid injection port, and the driving liquid is injected into the flow channel of each unit micro-channel structure through the through hole between the unit micro-channel structures;

[0129] S10: Inject liquid metal through the liquid injection port, and the liquid metal is injected into the flow channel of each unit micro-channel structure through the through hole between the unit micro-channel structures;

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

[0131] S12: A grounding plate is arranged under the flexible substrate;

[0132] S13: A driving control unit is arranged under the grounding plate, which is the same as the number of subarray micro-channels, and a driving control structure is formed, each driving control unit is connected with the corresponding liquid injection port, and a metasurface reflection unit is obtained.

[0133] Comparative example

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

[0135] The flexible upper cover plate, the flexible film, the flexible substrate, the grounding plate and the driving control structure are sequentially stacked;

[0136] The flexible substrate is provided with a micro-channel array structure and a liquid injection port, the micro-channel array structure comprises a plurality of unit micro-channel structures, the plurality of unit micro-channel structures are penetrated through by through holes, the unit micro-channel structure is a vertical cross-shaped structure, comprising a liquid pool and four mutually perpendicular rectangular cross arm flow channels, the liquid pool is located in the center of the micro-channel structure, and the four mutually perpendicular rectangular cross arm flow channels are arranged around the liquid pool; the unit micro-channel structure is as shown in Figure 7 ;

[0137] The flexible film is adhered to the flexible substrate by hot pressing, the flexible upper cover plate is adhered to the flexible film by spraying glue, and an air cavity structure with the same structure as the micro-channel structure is manufactured in the flexible upper cover plate;

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

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

[0140] Specifically, the flexible substrate, the flexible film and the flexible upper cover plate jointly 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] Specific parameters of the micro-channel array structure are as follows: the arrangement period P of the unit micro-channel structure is 15 mm, the width w1 of the rectangular cross arm flow channel is 0.2 mm, the length l2 of the flow channel is 5.9 mm, the width l1 of the liquid pool is 2 mm, the height t1 of the micro-channel array is 0.2 mm, and the liquid metal flow control angle is 0 mm < l0 < 6 mm.

[0143] The material of the flexible substrate 4, the flexible film 5 and the flexible upper cover plate 6 is SEBS rubber.

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

[0145] The driving liquid is a NaOH solution.

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

[0147] Figure 9 As can be seen from the frequency dynamic reconfigurable map of the super surface reflection unit of the present comparative example, with the liquid metal flowing in the micro-channel, the resonant frequency point of the unit can be reconfigured in the range of 6-12 GHz. Figure 10 As can be seen from the reflection phase range map of the super surface reflection unit of the present comparative example, in the 6-12 GHz wave band, the reflection phase control range of the unit satisfies 180°.

[0148] As can be seen from the comparison, with the liquid metal flowing in the micro-channel, the resonant frequency point of the super surface reflection unit of the present embodiment 2 or the present embodiment 3 can be reconfigured in the range of 4.5-12 GHz; with the liquid metal flowing in the micro-channel, the resonant frequency point of the super surface reflection unit of the comparative example can be reconfigured in the range of 6-12 GHz; the reconfigurable range of the super surface reflection unit of the present embodiment 2 or the present embodiment 3 is slightly wider than that of the comparative example. Figure 11 As can be seen from the comparison, the reflection phase control range of the super surface reflection unit of the present embodiment 2 or the present embodiment 3 is wider than that of the comparative example.

[0149] The above description is only the preferred embodiment of the present application, but the protection scope of the present application is not limited to this, any change or replacement within the technical range disclosed by the present application can be easily thought by those skilled in the art, which should be covered in the protection scope of the present application.

Claims

1. A liquid metal microchannel structure, characterized in that, It includes multiple unit microchannel structures, each unit microchannel structure being a curved cross-shaped structure, including a liquid storage tank and four semi-circular arc-shaped cross-arm channels; The liquid storage tank is located in the center of the microchannel structure. The four semi-circular cross-arm channels are arranged around the liquid storage tank and are interconnected through the liquid storage tank. All four semi-circular cross-arm channels extend away from the liquid storage tank. The four semi-circular cross arm flow channels include a first semi-circular cross arm flow channel, a second semi-circular cross arm flow channel, a third semi-circular cross arm flow channel, and a fourth semi-circular cross arm flow channel; The first and third semi-circular arc-shaped cross arm channels are symmetrically distributed at their centers, as are the second and fourth semi-circular arc-shaped cross arm channels. The angle between the first semi-circular cross arm flow channel and the second semi-circular cross arm flow channel is 90°, the angle between the second semi-circular cross arm flow channel and the third semi-circular cross arm flow channel is 90°, the angle between the third semi-circular cross arm flow channel and the fourth semi-circular cross arm flow channel is 90°, and the angle between the fourth semi-circular cross arm flow channel and the first semi-circular cross arm flow channel is 90°. The width w1 of the semi-circular arc-shaped cross arm flow channel is 0.2-0.6 mm, the arc radius r1 of the semi-circular arc-shaped cross arm flow channel is 3-3.5 mm, and the width l1 of the liquid storage tank is 1.5-2.5 mm. The liquid metal microchannel structure is an array structure, which includes multiple periodically arranged sub-array structures. The sub-array structures include... Individual microchannel structures, 3≤N≤5; The unit microchannel structures are interconnected, while the subarray structures are independent of each other and not connected. The liquid metal microchannel structure is used to reconstruct metasurface reflective units. The arc angle of the flow in the semi-circular cross-arm channel changes continuously within the range of 30° to 180°. The metasurface reflective unit using the liquid metal microchannel structure can achieve continuous reconstruction of the resonant frequency within the frequency range of 4.5 GHz to 12 GHz.

2. The liquid metal microchannel structure according to claim 1, characterized in that, The arrangement period of the unit microchannel structure is P, where P is 13-17 mm.

3. The liquid metal microchannel structure according to claim 2, characterized in that, The arrangement period of the subarray structure is P. x , where P x Satisfies: NP<Px≤(N+1)P.

4. A liquid metal reconfigurable metasurface reflective unit, characterized in that, The liquid metal reconfigurable metasurface unit includes the liquid metal microchannel structure according to any one of claims 1-3.

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