Microfluid metasurface based on liquid metal and preparation method thereof

Abstract

The invention discloses a liquid metal-based micro-fluid metasurface and a preparation method thereof, the liquid metal-based micro-fluid metasurface comprises a flexible packaging structure, a micro-channel structure and a driving control unit, the flexible packaging structure is provided with the micro-channel structure, the micro-channel structure is filled with liquid metal, and the driving control unit is arranged on the flexible packaging structure. Driving liquid is guided into the micro-channel structure through the driving control unit to control the flowing position and shape of the liquid metal; wherein the micro-channel structure comprises a T-shaped micro-channel and an I-shaped micro-channel, the center line of the T-shaped micro-channel and the center line of the I-shaped micro-channel coincide along the Y axis, and the T-shaped micro-channel and the I-shaped micro-channel are symmetrically arranged along the Y axis. The length change of the liquid metal in the composite flow channel is consistent, the angle insensitive characteristic is achieved while broadband frequency regulation and control are achieved, and the metasurface unit can achieve stable electromagnetic response under wide-angle incidence.

Description

Technical Field

[0001] The present invention relates to the technical field of artificial electromagnetic materials, and in particular to a liquid metal-based microfluidic super surface and a preparation method thereof. Background Art

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

[0003] The development of micro-nano technology has provided an effective way to prepare metasurface structures. After the design, processing and preparation of traditional metasurface structures, the material properties and electromagnetic wave response characteristics are fixed, making it difficult to achieve dynamic regulation 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 structures has gradually developed to achieve regulation of electromagnetic waves, but the above-mentioned metamaterials still have problems such as poor regulation stability, narrow regulation bandwidth, long regulation time, and limited regulation states.

[0004] Liquid metal-based metasurfaces provide a new approach to solving the problems of traditional metasurfaces. Liquid metal is a conductive metal that can flow at room temperature and has good dynamic reconfigurable properties. Liquid metal combines the excellent properties of traditional rigid and flexible materials. Through material ratio design, liquid metals with different melting points, conductivity and other properties can be designed specifically. Combined with the large deformation and fluidity of liquid metal, and integrated with microstructures, the continuous change of liquid metal morphology can be achieved. It has the characteristics of flexibility, low cost and reconfigurability. It is an emerging technology with great development prospects and can be widely used in flexible electronics, flexible sensors, reconfigurable antennas, metamaterials and other fields.

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

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide a liquid metal-based microfluidic metasurface and a preparation method thereof, in which the driving state of liquid metal in the flow channel is consistent, and the electromagnetic response is stable under a wide incident angle while achieving broadband frequency control.

[0007] To achieve the above-mentioned objectives, the first aspect of the present invention provides a liquid metal-based microfluidic metasurface, comprising a flexible packaging structure, a microfluidic channel structure and a drive control unit, wherein the microfluidic channel structure is arranged on the flexible packaging structure, the microfluidic channel structure is filled with liquid metal, and the drive control unit introduces a drive liquid into the microfluidic channel structure to control the flow position and shape of the liquid metal; wherein the microfluidic channel structure comprises a T-shaped microfluidic channel and an I-shaped microfluidic channel, the center lines of the T-shaped microfluidic channel and the I-shaped microfluidic channel coincide along the Y-axis, and the T-shaped microfluidic channel and the I-shaped microfluidic channel are symmetrically arranged along the Y-axis.

[0008] Furthermore, the microfluidic channel structure includes two T-shaped microfluidic channels and one I-shaped microfluidic channel, which are arranged in a row along the horizontal plane of the super surface in the order of one T-shaped microfluidic channel, one I-shaped microfluidic channel and one T-shaped microfluidic channel to form a T-I-T shaped composite channel.

[0009] Furthermore, the microfluidic channel structure includes two T-shaped microfluidic channels and two I-shaped microfluidic channels, which are arranged in a row along the horizontal plane of the super surface in the order of one T-shaped microfluidic channel, one I-shaped microfluidic channel, one I-shaped microfluidic channel and one T-shaped microfluidic channel to form a T-I-I-T-shaped composite channel.

[0010] Furthermore, the T-shaped microfluidic channel includes a horizontal branch and a vertical branch, the I-shaped microfluidic channel includes two horizontal branches and a vertical branch, the vertical branches of the T-shaped microfluidic channel and the I-shaped microfluidic channel overlap along the Y-axis, and the horizontal branches of the T-shaped microfluidic channel and the I-shaped microfluidic channel are the same length.

[0011] Furthermore, the depth and width of the horizontal branch of the T-shaped microchannel gradually increase from both ends to the middle, and the depth and width of the horizontal branch of the I-shaped microchannel gradually increase from both ends to the middle.

[0012] Furthermore, the width of the horizontal branch flow channel of the T-shaped microchannel varies in the range of 0.1 mm to 0.6 mm, and the depth of the horizontal branch flow channel of the T-shaped microchannel varies in the range of 0.01 mm to 0.5 mm.

[0013] Furthermore, the width of the horizontal branch flow channel of the I-shaped microchannel varies in the range of 0.1 mm to 0.6 mm, and the depth of the horizontal branch flow channel of the I-shaped microchannel varies in the range of 0.01 mm to 1.0 mm.

[0014] Furthermore, a cavity structure reserved for liquid metal deformation is arranged above the microchannel structure, and the cavity structure and the microchannel structure are separated by an elastic film.

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

[0016] Furthermore, the driving control unit is arranged below the metal reflecting plate and is connected to the microchannel structure via a flexible microtube.

[0017] A second aspect of the present invention provides a method for preparing the above-mentioned liquid metal-based microfluidic supersurface, characterized in that it comprises the following steps:

[0018] Forming a T-I-T type composite flow channel or a T-I-I-T type composite flow channel in the flexible packaging structure;

[0019] covering the composite flow channel with an elastic film;

[0020] A flexible packaging structure covering a reserved cavity structure on an elastic film;

[0021] A metal reflector is arranged below the flexible packaging structure having a composite flow channel;

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

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

[0024] The microfluidic structure of the present invention is configured as a composite flow channel composed of a T-type microfluidic channel and an I-type microfluidic channel, and the T-type microfluidic channel and the I-type microfluidic channel are configured symmetrically along the Y-axis, so that the flow channel lengths of the T-type microfluidic channel and the I-type microfluidic channel are the same, and the length of the liquid metal in the flow channel changes consistently. While achieving broadband frequency regulation, it has angle-insensitive characteristics, which helps the metasurface unit to achieve stable electromagnetic response under wide-angle incidence. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 A schematic structural diagram of a T-I-T type microfluidic metasurface according to an embodiment of the present invention;

[0027] Figure 2 A schematic structural diagram of a T-I-I-T type microfluidic metasurface according to an embodiment of the present invention;

[0028] Figure 3 for Figure 1 Schematic cross-section of the microfluidic metasurface;

[0029] Figure 4A partial enlarged view of a horizontal branch in a microchannel structure of a microfluidic supersurface according to an embodiment of the present invention;

[0030] Figure 5 for Figure 1 Schematic diagram of the dynamic response of liquid metal on microfluidic metasurface;

[0031] Figure 6 A reflection amplitude diagram of a T-I-T type microfluidic metasurface at 0° incidence according to an embodiment of the present invention;

[0032] Figure 7 A reflection amplitude diagram of a T-I-T type microfluidic metasurface at 30° incidence according to an embodiment of the present invention;

[0033] Figure 8 This is a comparison diagram of the reflection amplitudes of the T-I-I-T and T-I-T type microfluidic metasurfaces of the present invention at 0° incidence. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] like Figure 1As shown, the present invention provides a liquid metal-based microfluidic metasurface, including a flexible packaging structure 11, a microfluidic structure and a driving control unit 12, wherein the microfluidic structure is provided on the flexible packaging structure 11, and the microfluidic structure is filled with liquid metal 13, and the driving control unit 12 introduces a driving liquid 14 into the microfluidic structure to control the flow position and shape of the liquid metal 13. Specifically, the driving control unit 12 controls the flow control of the liquid metal 13 in the microfluidic channel in a manner including electromagnetic, voltage and / or pressure. Under the control of the control algorithm and the driving control circuit, the driving control unit 12 enables the liquid metal 13 to flow continuously in the flow channel, and the flow and fixed positions are controllable. Different flow positions represent different working states, and each microfluidic structure realizes multiple different working states under the flow reconstruction of the liquid metal 13. The metasurface units of different liquid metal 13 flow states are jointly encoded to achieve the regulation of the electromagnetic wave response. Among them, the microfluidic structure includes two T-shaped microfluidic channels 15 and one I-shaped microfluidic channel 16, which are arranged in a row along the horizontal plane of the super surface in the order of one T-shaped microfluidic channel 15, one I-shaped microfluidic channel 16 and one T-shaped microfluidic channel 15 to form a T-I-T type composite flow channel, the center lines of the T-shaped microfluidic channel 15 and the I-shaped microfluidic channel 16 coincide along the Y axis, and the T-shaped microfluidic channel 15 and the I-shaped microfluidic channel 16 are symmetrically arranged along the Y axis. In this embodiment, the T-shaped microfluidic channel and the I-shaped microfluidic channel are specially arranged in the above manner, so that the flow channel lengths of the T-shaped microfluidic channel and the I-shaped microfluidic channel are consistent, and the ends are aligned, so that the length changes of the liquid metal in the T-shaped microfluidic channel and the I-shaped microfluidic channel are controlled consistently by the driving control unit, and the angle-insensitive characteristics are achieved while achieving broadband frequency control. The T-I-T type composite structure is used to control the size of the liquid metal, and the symmetrical microfluidic structure design increases the control angle stability of the electromagnetic response under a wide incident angle.

[0036] like Figure 2 FIG. 1 is a microfluidic supersurface according to another embodiment of the present invention. Figure 1 The main difference is that the number of I-type microfluidics in the microfluidic structure is different. The microfluidic structure described in this embodiment includes two T-type microfluidics 15 and two I-type microfluidics 16, which are arranged in a row along the horizontal plane of the super surface in the order of one T-type microfluidic channel 15, one I-type microfluidic channel 16, one I-type microfluidic channel 16 and one T-type microfluidic channel 15 to form a T-I-I-T type composite flow channel, the center lines of the T-type microfluidic channel 15 and the I-type microfluidic channel 16 coincide along the Y axis, and the T-type microfluidic channel 15 and the I-type microfluidic channel 16 are symmetrically arranged along the Y axis.

[0037] The above-mentioned embodiments of the present invention broaden the frequency control range of the microfluidic metasurface by optimizing the design of the microchannel structure. Figure 2The T-I-I-T type composite flow channel structure in the embodiment can achieve S and C band resonant frequency control bandwidth of about 2.04 GHz based on the dimensional changes caused by the symmetrical flow of liquid metal. Figure 1 The T-I-T composite flow channel of the embodiment reduces the difficulty of unit design and processing while widening the frequency control bandwidth to 3.86 GHz (see Figure 6 ), and the symmetric design of the unit resonant structure enables it to maintain the stability of the electromagnetic response within 30° oblique incidence (see Figure 6 , Figure 7 , when the length of liquid metal in the branch is equal, the control frequency is consistent, and l0 in the figure is the length of liquid metal). Figure 8 As shown, from the comparison of the reflection amplitudes at 0° incidence of the two embodiments, it can be seen that the composite flow channels of the above two configurations can achieve the regulation of a wider bandwidth of the resonant frequency.

[0038] In a preferred embodiment of the present invention, the T-shaped microfluidic channel 15 includes a horizontal branch 151 and a vertical branch 152, and the I-shaped microfluidic channel includes two horizontal branches 161 and a vertical branch 162. The vertical branch 152 of the T-shaped microfluidic channel and the vertical branch 162 of the I-shaped microfluidic channel overlap along the Y axis, and the horizontal branch 151 of the T-shaped microfluidic channel and the horizontal branch 161 of the I-shaped microfluidic channel have the same length. In this embodiment, the horizontal branches of the T-shaped microfluidic channel and the I-shaped microfluidic channel have the same length, making it easier to control the consistency of the length change of the liquid metal in the T-shaped microfluidic channel and the I-shaped microfluidic channel, and reducing the difficulty of the drive control unit controlling the consistency of the length change of the liquid metal by introducing the drive liquid into the microfluidic channel structure.

[0039] The sizes of the T-shaped microchannel and the I-shaped microchannel of the composite microchannel in the above embodiment are relatively small, usually in the mm range, and based on the high surface tension characteristics of the liquid metal injected into the microchannel, when the flow channel structure sizes of each part of the T-shaped microchannel and the I-shaped microchannel are consistent, it is still difficult to adjust the length changes of the liquid metal in the T-shaped microchannel and the I-shaped microchannel to be consistent. In a preferred embodiment of the present invention, Figure 3 and 4 As shown, the depth and width of the horizontal branch of the T-shaped microchannel gradually increase from both ends to the middle, and the size change amplitude from both ends to the middle is the same. Since the depth and width of the horizontal branches of the I-shaped microchannel and the T-shaped microchannel gradually increase from both ends to the middle, the surface tension additional pressure of the "liquid metal-driving liquid" interface of the horizontal branch of the microchannel is different at different positions. For example, in the process of changing 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, and the change of the interface position causes the change of the additional pressure, and the liquid metal interface returns to the equilibrium symmetrical position through the generated pressure difference.

[0040] In a preferred embodiment of the present invention, the width of the horizontal branch channel 151 of the T-shaped microchannel 15 varies in the range of 0.1 mm to 0.6 mm, and the depth of the horizontal branch channel 151 of the T-shaped microchannel 15 varies in the range of 0.01 mm to 0.5 mm.

[0041] In a preferred embodiment of the present invention, the width of the horizontal branch channel 161 of the I-shaped microchannel 16 varies in the range of 0.1 mm to 0.6 mm, and the depth of the horizontal branch channel 161 of the I-shaped microchannel 16 varies in the range of 0.01 mm to 1.0 mm.

[0042] Figure 5 The three length states of liquid metal in the microchannel structure of the liquid metal-based microfluidic supersurface of the present invention are shown, which are the liquid metal full filling state, the liquid metal half filling state, and the liquid metal full contraction state from left to right, corresponding to three different dynamic responses of the supersurface. The driving liquid will compress the liquid metal toward the middle from both ends of the horizontal branch of the microchannel, which will cause the volume of the liquid metal in the middle of the microchannel to increase. In order to provide space for the liquid metal volume to change, in a preferred embodiment of the present invention, a cavity structure 18 reserved for the deformation of the liquid metal 13 is provided above the microchannel structure, and the cavity structure 18 is separated from the microchannel structure by an elastic film 19.

[0043] In a preferred embodiment of the present invention, a metal reflection plate 17 for reflecting incident electromagnetic waves is disposed below the flexible packaging structure 1, so that the metasurface unit structure can fully reflect the incident electromagnetic waves.

[0044] In a preferred embodiment of the present invention, the driving control unit 12 is disposed below the metal reflector 17 and connected to the microfluidic structure via a flexible microtube, which facilitates the connection arrangement between the driving control unit and the microfluidic structure and reduces manufacturing costs.

[0045] The present invention also provides a method for preparing the above-mentioned liquid metal-based microfluidic supersurface, which is characterized by comprising the following steps:

[0046] Forming a T-I-T type composite flow channel or a T-I-I-T type composite flow channel in the flexible packaging structure;

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

[0048] A flexible packaging structure covering a reserved cavity structure on an elastic film;

[0049] A metal reflective plate is arranged below the flexible packaging structure;

[0050] A driving control unit is arranged below the metal reflecting plate.

[0051] The flexible packaging structure is packaged by bonding to package the liquid metal and the driving liquid in the microfluidic structure to avoid leakage of the liquid metal and the driving liquid. The material of the flexible packaging structure can be PDMS, PMMA, PP, Flexdym, PC or PU.

[0052] The microfluidic structure is prepared in the flexible packaging structure of the metasurface. According to the electromagnetic wave response characteristics and the conventional metasurface configuration, the microfluidic structure and its parameters such as width and height are designed. The flow channel of the microfluidic structure is realized by micro-nano processing technology, including photolithography, nanoimprinting and other process methods.

[0053] In summary, the super-surface microfluidic structure of the present invention is configured as a composite flow channel composed of a T-type microfluidic channel and an I-type microfluidic channel, and the T-type microfluidic channel and the I-type microfluidic channel are configured to be symmetrically arranged along the Y axis, so that the flow channel lengths of the T-type microfluidic channel and the I-type microfluidic channel are the same, and the length changes of the liquid metal in the flow channel are consistent. While achieving broadband frequency regulation, it has angle-insensitive characteristics, which helps the super-surface unit to achieve stable electromagnetic response under wide-angle incidence. In addition, by configuring the structure and size of the T-type microfluidic channel and the I-type microfluidic channel, the super-surface microfluidic structure is designed as a T-I-T type composite flow channel, and the resonant frequency regulation bandwidth of the S and C band units is achieved based on the size changes caused by the flow of liquid metal. About 3.86GHz.

[0054] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implying the number of technical features indicated. Thus, the defined "first" and "second" features may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0055] A person skilled in the art will understand that all or part of the steps to implement the above embodiments may be accomplished by hardware or by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a disk or an optical disk, etc.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A liquid metal-based microfluidic supersurface, characterized in that: It comprises a flexible packaging structure, a microfluidic structure and a driving control unit, wherein the microfluidic structure is arranged on the flexible packaging structure, the microfluidic structure is filled with liquid metal, and the driving control unit introduces a driving liquid into the microfluidic structure to control the flow position and shape of the liquid metal; wherein the microfluidic structure comprises a T-shaped microfluidic channel and an I-shaped microfluidic channel, the center lines of the T-shaped microfluidic channel and the I-shaped microfluidic channel coincide with each other along the Y axis, and the T-shaped microfluidic channel and the I-shaped microfluidic channel are symmetrically arranged along the Y axis.

2. The liquid metal-based microfluidic supersurface according to claim 1, characterized in that: The microfluidic channel structure includes two T-shaped microfluidic channels and one I-shaped microfluidic channel, which are arranged in a row along the horizontal plane of the super surface in the order of one T-shaped microfluidic channel, one I-shaped microfluidic channel and one T-shaped microfluidic channel to form a T-I-T shaped composite channel.

3. The liquid metal-based microfluidic supersurface according to claim 1, characterized in that: The microfluidic channel structure includes two T-shaped microfluidic channels and two I-shaped microfluidic channels, which are arranged in a row along the horizontal plane of the super surface in the order of one T-shaped microfluidic channel, one I-shaped microfluidic channel, one I-shaped microfluidic channel and one T-shaped microfluidic channel to form a T-I-I-T shaped composite channel.

4. The liquid metal-based microfluidic supersurface according to claim 1, characterized in that: The T-shaped microfluidic channel includes a horizontal branch and a vertical branch, the I-shaped microfluidic channel includes two horizontal branches and a vertical branch, the vertical branches of the T-shaped microfluidic channel and the I-shaped microfluidic channel overlap along the Y axis, and the horizontal branches of the T-shaped microfluidic channel and the I-shaped microfluidic channel are the same in length.

5. The liquid metal-based microfluidic supersurface according to claim 4, characterized in that: The depth and width of the horizontal branch of the T-shaped microchannel gradually increase from both ends to the middle, and the depth and width of the horizontal branch of the I-shaped microchannel gradually increase from both ends to the middle.

6. The liquid metal-based microfluidic supersurface according to claim 5, characterized in that: The width of the horizontal branch flow channel of the T-shaped microchannel varies in the range of 0.1 mm to 0.6 mm, and the depth of the horizontal branch flow channel of the T-shaped microchannel varies in the range of 0.01 mm to 0.5 mm.

7. The liquid metal-based microfluidic supersurface according to claim 5, characterized in that: The width of the horizontal branch flow channel of the I-shaped microchannel varies in the range of 0.1 mm to 0.6 mm, and the depth of the horizontal branch flow channel of the I-shaped microchannel varies in the range of 0.01 mm to 1.0 mm.

8. The liquid metal-based microfluidic supersurface according to claim 1, characterized in that: A cavity structure reserved for deformation of liquid metal is arranged above the microchannel structure, and the cavity structure and the microchannel structure are separated by an elastic film.

9. The liquid metal-based microfluidic supersurface according to claim 1, characterized in that: A metal reflection plate for reflecting incident electromagnetic waves is arranged below the flexible packaging structure.

10. The liquid metal-based microfluidic supersurface according to claim 9, characterized in that: The driving control unit is arranged below the metal reflecting plate and is connected to the microchannel structure through a flexible microtube.

11. A method for preparing a liquid metal-based microfluidic supersurface according to any one of claims 1 to 10, characterized in that: The steps include: Forming a T-I-T type composite flow channel or a T-I-I-T type composite flow channel in the flexible packaging structure; covering the composite flow channel with an elastic film; A flexible packaging structure covering a reserved cavity structure on an elastic film; A metal reflective plate is arranged below the flexible packaging structure; A driving control unit is arranged below the metal reflecting plate.

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