Liquid metal-based microfluidic metasurface and method of manufacturing the same

Abstract

The application discloses a kind of microfluidic metasurface based on liquid metal and preparation method thereof, including flexible packaging structure, microchannel structure and drive control unit, the microchannel structure is provided on the flexible packaging structure, the microchannel structure is filled with liquid metal, and the flow position and shape of liquid metal are controlled by the drive control unit to microchannel structure Import driving liquid;Wherein, the microchannel structure includes T type microchannel and work type microchannel, the center line of T type microchannel and work type microchannel coincides along Y axis, and T type microchannel and work type microchannel are symmetrically arranged along Y axis.The length of liquid metal in the composite channel of the application is consistent, while realizing broadband frequency control, with angle-insensitive characteristics, which helps the super-surface unit to achieve stable electromagnetic response under wide-angle incidence.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of artificial electromagnetic materials, in particular to a microfluidic metasurface based on liquid metal and a preparation method thereof. BACKGROUND

[0002] As a new type of artificially designed composite microstructure, the metasurface has super physical properties that natural materials do not have. Through the design of material properties, shape structure, size, etc., the resonance characteristics of electromagnetic waves can be flexibly controlled, and the metasurface has broad application prospects in military and civilian fields such as optical sensing, radar camouflage stealth technology, aerospace communication, etc.

[0003] The development of micro-nano technology provides an effective way for the preparation of metasurface structure. The material properties and electromagnetic wave response characteristics of traditional metasurface structure are fixed after design, processing and preparation, and it is difficult to realize dynamic control of electromagnetic waves. In recent years, the use of conductive polymer materials, liquid crystal molecules, diodes, MEMS switches and other technologies to change the characteristics of metasurface structure has been gradually developed to realize the adjustment of electromagnetic waves. However, the above-mentioned super materials still have problems such as poor control stability, narrow control bandwidth, long control time, limited adjustment state, etc.

[0004] The metasurface based on liquid metal provides a new idea for solving the problems existing in traditional metasurface. Liquid metal is a conductive metal that can flow at room temperature and has good dynamic reconfigurable performance. Liquid metal combines the excellent performance of traditional rigid and flexible materials, and through material ratio design, liquid metal with different melting points and conductivity can be designed. Combined with the large deformation and flowability of liquid metal, the integration with microstructure can realize the continuous change of the shape of liquid metal, which has the characteristics of flexibility, low cost and reconfiguration. It is a promising emerging technology that can be widely used in flexible electronics, flexible sensing, reconfigurable antennas, metamaterials and other fields.

[0005] At present, the research on microfluidic metasurface based on liquid metal is still in its infancy. The reported microfluidic structure driving channel design is relatively simple, and the driving form of liquid metal is single. Moreover, due to the difficulty of driving and controlling liquid metal, the corresponding flow channel design is difficult, and the traditional liquid metal metasurface unit structure often has fewer flow channel branches, making it difficult to form a symmetrical structure, and the driving conditions of liquid metal in different branches are also difficult to keep consistent. The axisymmetric resonant structure is an important condition for realizing the stability of electromagnetic response of the unit under wide-angle incidence. SUMMARY

[0006] In view of the problems existing in the prior art, the purpose of the present application is to provide a microfluidic metasurface based on liquid metal and a preparation method thereof, which can drive liquid metal in the flow channel uniformly, realize wideband frequency adjustable control, and maintain the stability of electromagnetic response under wide-angle incidence.

[0007] To achieve the above object, the present application provides a liquid metal-based microfluidic metasurface, comprising a flexible packaging structure, a microfluidic structure and a driving control unit, the microfluidic structure is arranged on the flexible packaging structure, the microfluidic structure is filled with liquid metal, and the driving liquid is introduced into the microfluidic structure by the driving control unit to control the flow position and shape of the liquid metal; wherein the microfluidic structure comprises a T-shaped microfluidic channel and a T-shaped microfluidic channel, and the center lines of the T-shaped microfluidic channel and the T-shaped microfluidic channel coincide along the Y axis, and the T-shaped microfluidic channel and the T-shaped microfluidic channel are symmetrically arranged along the Y axis.

[0008] Further, the microfluidic structure comprises two T-shaped microfluidic channels and one T-shaped microfluidic channel, and the T-shaped microfluidic channels and the T-shaped microfluidic channel are arranged in a straight line along the horizontal plane of the metasurface in the order of one T-shaped microfluidic channel, one T-shaped microfluidic channel and one T-shaped microfluidic channel to form a T-T-T composite channel.

[0009] Further, the microfluidic structure comprises two T-shaped microfluidic channels and two T-shaped microfluidic channels, and the T-shaped microfluidic channels and the T-shaped microfluidic channel are arranged in a straight line along the horizontal plane of the metasurface in the order of one T-shaped microfluidic channel, one T-shaped microfluidic channel, one T-shaped microfluidic channel and one T-shaped microfluidic channel to form a T-T-T composite channel.

[0010] Further, the T-shaped microfluidic channel comprises a horizontal branch and a vertical branch, the T-shaped microfluidic channel comprises two horizontal branches and a vertical branch, the vertical branches of the T-shaped microfluidic channel and the T-shaped microfluidic channel coincide along the Y axis, and the horizontal branches of the T-shaped microfluidic channel and the T-shaped microfluidic channel have the same length.

[0011] Further, the depth and width of the horizontal branch of the T-shaped microfluidic channel gradually increase from both ends to the middle, and the depth and width of the horizontal branch of the T-shaped microfluidic channel gradually increase from both ends to the middle.

[0012] Further, the width of the horizontal branch of the T-shaped microfluidic channel changes in the range of 0.1mm-0.6mm, and the depth of the horizontal branch of the T-shaped microfluidic channel changes in the range of 0.01mm-0.5mm.

[0013] Further, the width of the horizontal branch of the T-shaped microfluidic channel changes in the range of 0.1mm-0.6mm, and the depth of the horizontal branch of the T-shaped microfluidic channel changes in the range of 0.01mm-1.0mm.

[0014] Further, a cavity structure is arranged above the microfluidic structure for reserving when the liquid metal deforms, and the cavity structure and the microfluidic structure are separated by an elastic film.

[0015] Further, a metal reflecting plate for reflecting incident electromagnetic waves is arranged below the flexible packaging structure.

[0016] Further, the driving control unit is arranged below the metal reflecting plate and connected to the microfluid channel structure through a flexible micro tube.

[0017] The second aspect of the present application provides a preparation method of the above-mentioned liquid metal-based microfluid super surface, characterized in that the method comprises the following steps:

[0018] A T-Work-T type composite channel or a T-Work-Work-T type composite channel is formed in the flexible packaging structure.

[0019] An elastic film is covered on the composite channel.

[0020] A flexible packaging structure with a reserved cavity structure is covered on the elastic film.

[0021] A metal reflecting plate is arranged below the flexible packaging structure with the composite channel.

[0022] A driving control unit is arranged below the metal reflecting plate.

[0023] Further, the material of the flexible packaging structure is plastic, silicone rubber or elastomer.

[0024] The microfluid channel structure of the present application is configured as a composite channel composed of a T-shaped microfluid channel and a Work-shaped microfluid channel, and the T-shaped microfluid channel and the Work-shaped microfluid channel are arranged symmetrically along the Y axis, so that the lengths of the T-shaped microfluid channel and the Work-shaped microfluid channel are the same, the length of the liquid metal in the channel changes uniformly, and the wideband frequency control is realized while the angle insensitivity is achieved, which helps the super surface unit to achieve stable electromagnetic response under wide-angle incidence. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0026] Figure 1 FIG. 1 is a structure schematic diagram of a T-Work-T type microfluid super surface according to an embodiment of the present application;

[0027] Figure 2 FIG. 2 is a structure schematic diagram of a T-Work-Work-T type microfluid super surface according to an embodiment of the present application;

[0028] Figure 3 FIG. 3 is a cross-sectional schematic diagram of a microfluid super surface according to an embodiment of the present application; Figure 1

[0029] Figure 4 ​A partial enlarged view of the horizontal branch in the microfluid channel structure of the microfluid super surface of an embodiment of the present application;

[0030] Figure 5 For Figure 1 A schematic diagram of the dynamic response of the microfluid super surface liquid metal;

[0031] Figure 6 Reflection amplitude diagram of the T-W-T type microfluid super surface of an embodiment of the present application at 0° incidence;

[0032] Figure 7 Reflection amplitude diagram of the T-W-T type microfluid super surface of an embodiment of the present application at 30° incidence;

[0033] Figure 8 Reflection amplitude comparison diagram of the T-W-W-T and T-W-T type microfluid super surfaces of the present application at 0° incidence. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0035] As Figure 1As shown, this invention provides a microfluidic metasurface based on liquid metal, comprising a flexible encapsulation structure 11, a microchannel structure, and a drive control unit 12. The microchannel structure is disposed on the flexible encapsulation structure 11, and liquid metal 13 is filled in the microchannel structure. The drive control unit 12 introduces a driving fluid 14 into the microchannel structure to control the flow position and shape of the liquid metal 13. Specifically, the drive control unit 12 controls the flow of liquid metal 13 in the microchannel using electromagnetic, voltage, and / or pressure methods. Under the control of the control algorithm and drive control circuit, the drive control unit 12 enables the liquid metal 13 to flow continuously in the flow channel, with controllable flow and fixed positions. Different flow positions represent different working states, and each microchannel structure achieves multiple different working states under the flow reconstruction effect of liquid metal 13. The metasurface units with different liquid metal 13 flow states are co-encoded to achieve regulation of electromagnetic wave response. The microchannel structure includes two T-shaped microchannels 15 and one I-shaped microchannel 16, arranged in a straight line along the horizontal plane of the metasurface to form a T-I-T composite channel. The centerlines of the T-shaped microchannels 15 and I-shaped microchannels 16 coincide along the Y-axis, and the T-shaped microchannels 15 and I-shaped microchannels 16 are symmetrically arranged along the Y-axis. In this embodiment, by arranging the T-shaped and I-shaped microchannels in this special manner, the channel lengths of the T-shaped and I-shaped microchannels are consistent and their ends are aligned. This facilitates the consistent control of the liquid metal length changes in the T-shaped and I-shaped microchannels through the drive control unit, achieving broadband frequency control while maintaining angle insensitivity. The T-I-T composite structure is used to control the size of the liquid metal, and the symmetrical microchannel structure design increases the stability of the control angle of the electromagnetic response under wide incident angles.

[0036] like Figure 2 As shown, this is a microfluidic metasurface according to another embodiment of the present invention, which is similar to... Figure 1 The main difference lies in the number of I-shaped microchannels in the microchannel structure. The microchannel structure described in this embodiment includes two T-shaped microchannels 15 and two I-shaped microchannels 16, which are arranged in a line along the horizontal plane of the metasurface in the order of one T-shaped microchannel 15, one I-shaped microchannel 16, one I-shaped microchannel 16 and one T-shaped microchannel 15 to form a T-I-I-T composite channel. The center lines of the T-shaped microchannels 15 and the I-shaped microchannels 16 coincide along the Y-axis, and the T-shaped microchannels 15 and the I-shaped microchannels 16 are symmetrically arranged along the Y-axis.

[0037] The above embodiments of the present invention have broadened the frequency control range of microfluidic metasurfaces by optimizing the microchannel structure. Figure 2The T-W-T composite flow channel structure in the embodiments can achieve a S, C band resonant frequency regulation bandwidth of about 2.04 GHz based on the size change caused by the symmetrical flow of liquid metal. Figure 1 The T-W-T composite flow channel of the embodiments can reduce the design and processing difficulty of the unit, and expand the frequency regulation bandwidth to 3.86 GHz (see Figure 6 ), and the symmetrical design of the unit resonant structure can keep the stability of the electromagnetic response under 30° oblique incidence (see Figure 6 、 Figure 7 When the lengths of the liquid metal in the branches are equal, the regulation frequency is consistent, and l0 in the figure is the length of the liquid metal. Figure 8 As shown in the comparative reflection amplitude comparison chart of 0° incidence of the two embodiments, the composite flow channels of the above two configurations can both achieve the regulation of a resonant frequency with a wide bandwidth.

[0038] In a preferred embodiment of the present application, the T-shaped micro channel 15 includes a horizontal branch 151 and a vertical branch 152, the W-shaped micro channel includes two horizontal branches 161 and a vertical branch 162, the vertical branch 152 of the T-shaped micro channel and the vertical branch 162 of the W-shaped micro channel coincide along the Y axis, and the lengths of the horizontal branch 151 of the T-shaped micro channel and the horizontal branch 161 of the W-shaped micro channel are the same. In this embodiment, the lengths of the horizontal branches of the T-shaped micro channel and the W-shaped micro channel are the same, making it easier to regulate the length changes of the liquid metal in the T-shaped micro channel and the W-shaped micro channel consistently, and reducing the difficulty of the driving control unit in controlling the length change consistency of the liquid metal by introducing driving liquid into the micro channel structure.

[0039] The composite micro channel T-shaped micro channel and W-shaped micro channel in the above embodiments are usually mm level in size, and based on the high surface tension characteristics of the liquid metal injected into the micro channel, it is still difficult to adjust the length changes of the liquid metal in the T-shaped micro channel and the W-shaped micro channel to be consistent when the sizes of the flow channel structures in each part of the T-shaped micro channel and the W-shaped micro channel are consistent. In a preferred embodiment of the present application, as shown in Figure 3 and 4 The depth and width of the horizontal branch of the T-shaped micro channel gradually increase from both ends to the middle, and the size change amplitude is the same from both ends to the middle. Since the depth and width of the horizontal branch of the T-shaped micro channel gradually increase from both ends to the middle, the surface tension additional pressure of the "liquid metal-driving liquid" interface in the micro channel horizontal branch is different at different positions, such as the change of the length of the liquid metal under the control of the driving control unit, the "liquid metal-driving liquid" interface in the flow channel moves asymmetrically, the change of the interface position causes the change of the additional pressure, and the pressure difference causes the liquid metal interface to return to the balanced symmetric position.

[0040] In a preferred embodiment of the present application, the width of the horizontal branch flow channel 151 of the T-shaped micro flow channel 15 ranges from 0.1 mm to 0.6 mm, and the depth of the horizontal branch flow channel 151 of the T-shaped micro flow channel 15 ranges from 0.01 mm to 0.5 mm.

[0041] In a preferred embodiment of the present application, the width of the horizontal branch flow channel 161 of the H-shaped micro flow channel 16 ranges from 0.1 mm to 0.6 mm, and the depth of the horizontal branch flow channel 161 of the H-shaped micro flow channel 16 ranges from 0.01 mm to 1.0 mm.

[0042] Figure 5 The present application shows three length states of the liquid metal in the micro flow channel structure in the liquid metal-based micro fluid super surface, from left to right, they are liquid metal full filling state, liquid metal half filling state, and liquid metal full shrinkage state, corresponding to three different dynamic responses of the super surface. The driving liquid will compress the liquid metal to the middle from both ends of the horizontal branch of the micro flow channel, which will cause the volume of the liquid metal at the middle part of the micro flow channel to increase. In order to provide space for the volume change of the liquid metal, in a preferred embodiment of the present application, a cavity structure 18 is arranged above the micro flow channel structure for reserving the deformation of the liquid metal 13, and the cavity structure 18 is separated from the micro flow channel structure by an elastic film 19.

[0043] In a preferred embodiment of the present application, a metal reflection plate 17 is arranged below the flexible packaging structure 1, which can make the super surface unit structure totally reflect the incident electromagnetic wave.

[0044] In a preferred embodiment of the present application, the driving control unit 12 is arranged below the metal reflection plate 17 and connected to the micro flow channel structure through a flexible micro tube. In this way, the connection and arrangement of the driving control unit and the micro flow channel structure can be facilitated, and the manufacturing cost can be reduced.

[0045] The present application also provides a preparation method of the above-mentioned liquid metal-based micro fluid super surface, characterized by comprising the following steps:

[0046] forming a T-H-T composite flow channel or a T-H-H-T composite flow channel in the flexible packaging structure;

[0047] covering an elastic film on the composite flow channel;

[0048] covering a flexible packaging structure with a reserved cavity structure on the elastic film;

[0049] arranging a metal reflection plate below the flexible packaging structure;

[0050] arranging a driving control unit below the metal reflection plate.

[0051] The flexible packaging structure is packaged by bonding to encapsulate the liquid metal and the driving liquid in the micro-channel structure, so as to avoid leakage of the liquid metal and the driving liquid.

[0052] The micro-channel structure is prepared in the flexible packaging structure of the metasurface, and the micro-channel structure and parameters such as width and height thereof are designed according to a conventional metasurface configuration in terms of electromagnetic wave response characteristics.

[0053] In summary, the metasurface micro-channel structure of the present application is configured as a composite channel composed of a T-shaped micro-channel and a T-shaped micro-channel, and the T-shaped micro-channel and the T-shaped micro-channel are symmetrically arranged along the Y axis, so that the flow channel length of the T-shaped micro-channel and the T-shaped micro-channel is the same, and the length of the liquid metal in the flow channel changes uniformly, which realizes broadband frequency regulation while having angle-insensitive characteristics, and helps the metasurface unit to achieve stable electromagnetic response under wide-angle incidence. In addition, by configuring the structure and size of the T-shaped micro-channel and the T-shaped micro-channel, the metasurface micro-channel structure is designed as a T-T-shaped composite channel, and the size change caused by the flow of the liquid metal realizes the S, C-band unit resonance frequency regulation bandwidth of about 3.86GHz.

[0054] The terms "first", "second", "third", etc. are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implying the number of the indicated technical features. Therefore, the features of "first", "second" defined above can be explicitly or implicitly included one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0055] Those of ordinary skill in the art can understand that all or part of the steps of the above-mentioned embodiments can be completed by hardware, or by programs instructing relevant hardware to complete, and the programs can be stored in a computer readable storage medium, and the storage medium mentioned above can be a read-only memory, a magnetic disk or an optical disk, etc.

[0056] The above only describes the preferred embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A microfluidic metasurface based on liquid metal, characterized in that, The device includes a flexible packaging structure, a microfluidic structure, and a drive control unit. The microfluidic structure is disposed on the flexible packaging structure and filled with liquid metal. The drive control unit introduces a driving fluid into the microfluidic structure to control the flow position and shape of the liquid metal. The microfluidic structure includes T-shaped microfluidics and I-shaped microfluidics. The centerlines of the T-shaped and I-shaped microfluidics coincide along the Y-axis and are symmetrically arranged along the Y-axis. The T-shaped microfluidic channel includes horizontal and vertical branches, and the I-shaped microfluidic channel includes two horizontal and vertical branches. The vertical branches of the T-shaped and I-shaped microfluidics coincide along the Y-axis, and the horizontal branches of the T-shaped and I-shaped microfluidics have the same length. The depth and width of the horizontal branches of the T-shaped and I-shaped microfluidics gradually increase from both ends towards the middle, and the depth and width of the horizontal branches of the I-shaped microfluidics also gradually increase from both ends towards the middle.

2. The microfluidic metasurface based on liquid metal as described in claim 1, characterized in that, The microchannel structure includes two T-shaped microchannels and one I-shaped microchannel, which are arranged in a line along the horizontal plane of the metasurface in the order of one T-shaped microchannel, one I-shaped microchannel and one T-shaped microchannel to form a T-I-T composite channel.

3. The microfluidic metasurface based on liquid metal as described in claim 1, characterized in that, The microchannel structure includes two T-shaped microchannels and two I-shaped microchannels, which are arranged in a line along the horizontal plane of the metasurface in the order of one T-shaped microchannel, one I-shaped microchannel, one I-shaped microchannel and one T-shaped microchannel to form a T-I-I-T composite channel.

4. The microfluidic metasurface based on liquid metal as described in claim 1, characterized in that, The width of the horizontal branch channels of the T-shaped microchannel varies from 0.1mm to 0.6mm, and the depth of the horizontal branch channels of the T-shaped microchannel varies from 0.01mm to 0.5mm.

5. The microfluidic metasurface based on liquid metal as described in claim 1, characterized in that, The width of the horizontal branch channels of the I-shaped microchannel varies from 0.1mm to 0.6mm, and the depth of the horizontal branch channels of the I-shaped microchannel varies from 0.01mm to 1.0mm.

6. The microfluidic metasurface based on liquid metal as described in claim 1, characterized in that, The microchannel structure has a cavity structure above it for the deformation of liquid metal, and the cavity structure is separated from the microchannel structure by an elastic film.

7. The microfluidic metasurface based on liquid metal as described in claim 1, characterized in that, A metal reflector is disposed below the flexible packaging structure to reflect incident electromagnetic waves.

8. The microfluidic metasurface based on liquid metal as described in claim 7, characterized in that, The drive control unit is located below the metal reflector and is connected to the microchannel structure via a flexible microtube.

9. A method for preparing a microfluidic metasurface based on liquid metal as described in any one of claims 1-8, characterized in that, Includes the following steps: A T-I-T type composite flow channel or a T-I-I-T type composite flow channel is formed in the flexible packaging structure; An elastic film is covered on the composite flow channel; A flexible encapsulation structure with a pre-reserved cavity structure covered on an elastic film; A metal reflector is placed below the flexible packaging structure; A drive control unit is located below the metal reflector.

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