Flexible conformal passive sensor based on spiral microstructure metamaterial and design method

Abstract

The invention discloses a flexible conformal passive sensor based on a spiral microstructure metamaterial and a design method, and relates to the technical field of metamaterial sensors. The flexible conformal passive sensor comprises a three-dimensional structure composed of a plurality of unit cell structures which are periodically arranged in a plane; each unit cell structure comprises a first cubic block and a spiral microstructure connected with the side edge of the first cubic block; a point defect structure is arranged in the center of the three-dimensional structure and comprises a second cube block and a spiral microstructure connected with the side edge of the second cube block; the side length of the second cubic block is greater than that of the first cubic block; an energy storage element is arranged on the point defect structure, a piezoelectric material is arranged on the side edge of the point defect structure, and a sensor is arranged on the unit cell structure; the piezoelectric material is electrically connected with the energy storage element, and the energy storage element is electrically connected with the sensor. The technical problem that a traditional sensor cannot be directly applied to a flexible and elastic large-deformation surface is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of metamaterial sensors, and in particular to a flexible conformal passive sensor based on spiral microstructure metamaterial and a design method thereof. Background Art

[0002] With the growing demand for new material performance and the continuous development of new preparation processes, the design and synthesis of metamaterials with special properties has gradually become a research hotspot. Metamaterials generally refer to artificial functional materials that use conventional natural materials as a substrate, using artificially designed microstructures as basic units, and through periodic arrangement, achieve special properties that are rare or not found in natural materials. The unusual special properties of metamaterials are determined by the geometric configuration of their microstructures and are influenced by design parameters and component materials, but are not related to the properties of the component materials themselves. Research on metamaterials is widely carried out in fields such as mechanics, thermodynamics, acoustics, and optics, and its application areas include aerospace, rail transportation, and many other fields.

[0003] Flexible electronics technology is currently developing rapidly, with breakthroughs continuously being made in technologies such as smart skin, electronic skin, and flexible electronic devices. With the advent of the Internet of Everything (IoE), flexible capacitive pressure sensors, due to their high sensitivity, high stability, and low power consumption, hold great promise for applications in areas such as human-computer interaction, health monitoring, and wearable electronics. In biomedicine, the use of liquid metal hydrogels to construct electronic interfaces that are compatible with tissue mechanics and have interfacial chemistry that is friendly to bioelectronic interfaces offers significant advantages in flexible electronics applications. In the field of metamaterials, flexible structures are also attracting attention due to their strong adaptability. However, current flexible electronic designs are still limited by energy sources, and flexible sensors require additional external circuitry. Furthermore, current "flexibility" primarily refers to the ability of sensors to operate on curved surfaces with a certain degree of curvature; however, situations where the working surface itself experiences in-plane deformation remain difficult to achieve.

[0004] For energy harvesting using acoustic metamaterials, most currently implemented using phononic crystal plate structures, of which there are three main approaches: the first approach is to utilize the defect state characteristics of phononic crystals to introduce point defects or line defects in their periodic supercells to produce waveguide or energy localization effects, and combine with piezoelectric ceramic materials to obtain electrical energy; the second approach is to utilize the negative refractive index characteristics of phononic crystals to arrange single crystals with different structural parameters into a gradient, guide the waves to focus on a specific target area, and then combine with piezoelectric ceramic materials to convert the focused mechanical energy into electrical energy; the third approach is to utilize the local resonance characteristics of locally resonant phononic crystals to concentrate the elastic wave energy inside the structure in a specific vibration mode, and then combine with piezoelectric materials to realize the conversion of mechanical energy into electrical energy. The above energy harvesting methods are all limited by the structure and cannot be applied in actual scenarios. Summary of the Invention

[0005] To address the technical problem that traditional sensors cannot be directly applied to flexible, elastic, and highly deformable surfaces, the present invention provides a flexible, conformal passive sensor and design method based on a spiral microstructured metamaterial. The technical solution is as follows:

[0006] On the one hand, a flexible conformal passive sensor based on a spiral microstructure metamaterial is provided, comprising a three-dimensional structure composed of a plurality of unit cell structures periodically arranged in a plane, wherein the unit cell structure comprises a first cubic block and a spiral microstructure connected to the side of the first cubic block; a point defect structure is arranged at the center of the three-dimensional structure, wherein the point defect structure comprises a second cubic block and a spiral microstructure connected to the side of the second cubic block; the side length of the second cubic block is greater than the side length of the first cubic block; an energy storage element is arranged on the point defect structure, a piezoelectric material is arranged on the side of the point defect structure, and a sensor is arranged on the unit cell structure; the piezoelectric material is electrically connected to the energy storage element, and the energy storage element is electrically connected to the sensor.

[0007] Optionally, the density of the second cubic block is greater than the density of the first cubic block.

[0008] Optionally, the unit cell structure includes a first cubic block and four spiral microstructures, the four spiral microstructures are respectively connected to four side surfaces of the first cubic block, and the four spiral microstructures are arranged in a cross shape.

[0009] Optionally, the point defect structure includes a second cubic block and four spiral microstructures, the four spiral microstructures are respectively connected to four side surfaces of the second cubic block, and the four spiral microstructures are arranged in a cross shape.

[0010] Optionally, connecting hemispheres are provided at the connecting ends between adjacent spiral microstructures as nodes.

[0011] Optionally, the piezoelectric material is disposed within a spiral microstructure connected to the second cubic block.

[0012] Optionally, the axis equation of the spiral microstructure includes an ideal spiral line equation of the middle section and transition joint curve equations at both ends.

[0013] On the other hand, a design method for a flexible conformal passive sensor based on a spiral microstructure metamaterial is also provided, including: designing a spiral microstructure using metamaterial as the material based on the axis equation of the spiral structure; connecting multiple spiral microstructures through a first cubic block as a connection point to design a unit cell structure; arranging the unit cell structure periodically in a plane, and using two connecting hemispheres as nodes at the connection between adjacent unit cell structures to form a complete sphere to design a three-dimensional structure; replacing the first cubic block of the unit cell structure at the center of the three-dimensional structure with a second cubic block to obtain a point defect design of a finite period structure; respectively installing sensors, energy storage elements and piezoelectric materials on the first cubic block, the second cubic block and the spiral microstructure connected to the second cubic block, and electrically connecting the energy storage element to the sensor and the piezoelectric material, respectively, to obtain a passive sensor.

[0014] Optionally, based on the spiral structure axis equation, a spiral microstructure is designed using metamaterial as the material, including: establishing an ideal spiral line equation curve and adding transition joint curves at both ends of the ideal spiral line equation curve to obtain the spiral structure axis equation; based on the spiral structure axis equation and the metamaterial, the spiral microstructure is designed by sweeping a circular surface.

[0015] Optionally, multiple spiral microstructures are connected through a first cubic block as a connection point to design a unit cell structure, including: taking the center of one end face of the spiral microstructure as the rotation center and arranging them at 90° intervals to obtain a cross-shaped structure; establishing a first cubic block with the center position of the cross-shaped structure as the center, and establishing connecting hemispheres at the centers of the four circular cross sections outside the cross-shaped structure to obtain a unit cell structure.

[0016] An embodiment of the present invention provides a flexible conformal passive sensor and design method based on spiral microstructure metamaterials. A flexible passive sensor capable of adapting to large deformations is designed, integrating three functions: flexible conformality, energy harvesting, and sensing. This solves the problem of being unable to install sensors in special occasions and makes it possible to perform sensing on surfaces that are prone to large elastic deformations. The passive design of the present invention makes the application of sensors more convenient and efficient, and can avoid the extra weight brought by complex conductive circuits in occasions with high lightweight requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 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.

[0018] Figure 11 is a schematic diagram of a three-dimensional structure of a flexible conformal passive sensor based on a spiral microstructure metamaterial provided by an embodiment of the present invention;

[0019] Figure 2 is a schematic diagram of a unit cell structure provided by an embodiment of the present invention;

[0020] Figure 3 is a schematic diagram of a spiral microstructure provided by an embodiment of the present invention;

[0021] Figure 4 1 is a schematic diagram of the overall structure of a flexible conformal passive sensor based on a spiral microstructure metamaterial provided by an embodiment of the present invention;

[0022] Figure 5 This is a flow chart of a design method for a flexible conformal passive sensor based on a spiral microstructure metamaterial provided by an embodiment of the present invention;

[0023] Figure 6 Schematic diagram of a dispersion curve and a transmission characteristic-frequency curve provided by an embodiment of the present invention.

[0024] In the figure, 1. Unit cell structure, 11. First cubic block, 12. Spiral microstructure, 13. Connecting hemisphere, 2. Point defect structure, 21. Second cubic block, 3. Energy storage element, 4. Piezoelectric material, 5. Sensor. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0026] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as an "exemplary" in the present invention should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of the word "exemplary" is intended to present concepts in a concrete manner. Furthermore, in the embodiments of the present invention, "and / or" can mean both or either of the two.

[0027] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0028] Figure 1 Schematic diagram of a three-dimensional structure of a flexible conformal passive sensor based on a spiral microstructure metamaterial according to an embodiment of the present invention. Figure 1 Figure (a) is a top view. Figure 1 Figure (b) is an isometric view. Figure 1As shown, it includes a three-dimensional structure composed of multiple unit cell structures 1 periodically arranged in a plane, and a point defect structure 2 is set at the center of the three-dimensional structure.

[0029] Figure 2 Schematic diagram of a unit cell structure provided according to an embodiment of the present invention. Figure 2 Figure (a) is a top view of the unit cell structure 1. Figure 2 Figure (b) is the left view of the unit cell structure 1. Figure 2 Figure (c) is the front view of the unit cell structure 1. Figure 2 Figure (c) is an isometric view of the unit cell structure 1. Figure 2 As shown, the unit cell structure 1 includes a first cubic block 11 and a spiral microstructure 12 connected to the side of the first cubic block 11.

[0030] Specifically, the unit cell structure 1 includes a first cubic block 11 and four spiral microstructures 12 . The four spiral microstructures 12 are respectively connected to four side surfaces of the first cubic block 11 , and the four spiral microstructures 12 are arranged in a cross shape.

[0031] like Figure 2 As shown, the connecting ends between adjacent spiral microstructures 12 are provided with connecting hemispheres 13 as nodes.

[0032] In the embodiment of the present invention, the point defect structure 2 is consistent with the overall structure of the unit cell structure 1. Figure 2 , the difference is that the first cubic block 11 is replaced by a second cubic block 21. Specifically, the point defect structure 2 includes the second cubic block 21 and the spiral microstructure 12 connected to the side of the second cubic block 21. The side length of the second cubic block 21 is greater than the side length of the first cubic block 11. For example, the side length of the second cubic block 21 is several times the side length of the first cubic block 11.

[0033] Specifically, the point defect structure 2 includes a second cubic block 21 and four spiral microstructures 12 . The four spiral microstructures 12 are respectively connected to four side surfaces of the second cubic block 21 , and the four spiral microstructures 12 are arranged in a cross shape.

[0034] Preferably, the density of the second cubic block 21 is greater than that of the first cubic block 11. For example, the second cubic block 21 is made of 45 steel.

[0035] Figure 3 FIG. 1 is a schematic diagram of a spiral microstructure provided according to an embodiment of the present invention. Figure 3 As shown, d0 is the cross-sectional diameter, r0 is the spiral radius, L0 is the total length of the spiral microstructure 12, N0 is the number of spirals, p0 is the spacing between the spirals, and p j is the length of the joint part.

[0036] Specifically, such as Figure 3 As shown, the axis equation of the spiral microstructure 12 includes the ideal spiral line equation in the middle section and the transition joint curve equations at both ends, wherein the transition joint curve smoothly transitions from the boundary of the ideal spiral line to the center point of the spiral line.

[0037] Specifically, the material of the spiral microstructure 12 may be, for example, polymer, photosensitive resin, rubber, or the like.

[0038] Figure 4 FIG. 1 is a schematic diagram of the overall structure of a flexible conformal passive sensor based on a spiral microstructure metamaterial according to an embodiment of the present invention. Figure 4 As shown, an energy storage element 3 is arranged on the point defect structure 2, a piezoelectric material 4 is arranged on the side of the point defect structure 2, and a sensor 5 is arranged on the unit cell structure 1; the piezoelectric material 4 is electrically connected to the energy storage element 3, and the energy storage element 3 is electrically connected to the sensor 5.

[0039] Specifically, such as Figure 4 As shown, the piezoelectric material 4 is disposed in the spiral microstructure 12 connected to the second cubic block 21 .

[0040] Optionally, the piezoelectric material 4 includes PVDF piezoelectric material.

[0041] Optionally, the number of sensors 5 can be changed as needed.

[0042] Optionally, the sensor 5 includes an inertial measurement unit (IMU) sensor for deformation, navigation, motion posture perception, etc.

[0043] The flexible conformal passive sensor based on spiral microstructure metamaterial provided by the embodiment of the present invention can be used on flexible and elastic surfaces such as various floating aircraft and air-membrane pavilions. The elastic deformation of the elastic surface drives the piezoelectric material 4 to generate electrical energy, which is then used to charge the energy storage element 3, and then the energy storage element 3 is used to power the sensor 5, thereby realizing the passive design of the sensor.

[0044] Figure 5 FIG. 1 is a flow chart of a design method of a flexible conformal passive sensor based on a spiral microstructure metamaterial according to an embodiment of the present invention. Figure 5 As shown, the method specifically includes the following steps:

[0045] Step S502 is to design a spiral microstructure using metamaterials based on the spiral structure axis equation. Specifically, the process includes the following steps:

[0046] Step S5021, establishing an ideal helix equation curve and adding transition joint curves at both ends of the ideal helix equation curve to obtain the helical structure axis equation;

[0047] Step S5022: Based on the spiral structure axis equation and the metamaterial, a spiral microstructure is designed by sweeping a circular surface.

[0048] Step S504: Connect the multiple spiral microstructures using the first cubic block as a connection point to design a unit cell structure. Specifically, the steps include:

[0049] Step S5041, taking the center of one end face of the spiral microstructure as the rotation center and forming an array at intervals of 90 degrees to obtain a cross-shaped structure;

[0050] Step S5042: Establish a first cubic block with the center of the cross-shaped structure as the center, and establish connecting hemispheres at the centers of the four circular cross sections outside the cross-shaped structure to obtain a unit cell structure.

[0051] In step S506 , the unit cell structures are periodically arranged in a plane, and the connections between adjacent unit cell structures are formed by combining two connected hemispheres into a complete sphere as a node, thereby designing a three-dimensional structure.

[0052] For example, the unit cell structures are arranged five by five in a plane, and the connections between the unit cell structures are made by combining two connected hemispheres into a complete sphere as nodes to obtain a three-dimensional structure.

[0053] Step S508 : replacing the first cubic block of the unit cell structure at the center of the three-dimensional structure with the second cubic block to obtain a point defect design of a finite period structure.

[0054] Step S510 , respectively installing sensors, energy storage elements and piezoelectric materials on the first cubic block, the second cubic block and the spiral microstructure connected to the second cubic block, and electrically connecting the energy storage elements to the sensors and the piezoelectric materials to obtain passive sensors.

[0055] The point defect design in the present invention is used to analyze the frequency characteristics and transmission characteristics, and the dispersion curve and transmission characteristic-frequency curve are obtained as shown in FIG. Figure 6 As shown, the peak in the curve indicates that the external vibration energy is collected by the structure of the passive sensor, realizing the energy capture function of the passive sensor.

[0056] As can be seen from the foregoing description, embodiments of the present invention provide a flexible, conformal passive sensor and design method based on a helical microstructured metamaterial. These sensors can adapt to in-plane tensile deformation of elastic surfaces while maintaining stable passive operation under tensile deformation. The passive sensor of the present invention can operate normally within the elastic deformation range of 0 to 1% strain, and its energy capture efficiency improves with increasing deformation.

[0057] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A flexible conformal passive sensor based on spiral microstructure metamaterial, characterized in that: A three-dimensional structure comprising a plurality of unit cell structures periodically arranged in a plane, wherein the unit cell structure comprises a first cubic block and a spiral microstructure connected to a side of the first cubic block; a point defect structure is provided at the center of the three-dimensional structure, wherein the point defect structure comprises a second cubic block and a spiral microstructure connected to a side of the second cubic block; and the side length of the second cubic block is greater than the side length of the first cubic block; An energy storage element is arranged on the point defect structure, a piezoelectric material is arranged on the side of the point defect structure, and a sensor is arranged on the unit cell structure; the piezoelectric material is electrically connected to the energy storage element, and the energy storage element is electrically connected to the sensor.

2. The flexible conformal passive sensor based on spiral microstructure metamaterial according to claim 1, characterized in that: The density of the second cubic block is greater than the density of the first cubic block.

3. The flexible conformal passive sensor based on spiral microstructure metamaterial according to claim 1, characterized in that: The unit cell structure includes a first cubic block and four spiral microstructures. The four spiral microstructures are respectively connected to the four side surfaces of the first cubic block, and the four spiral microstructures are arranged in a cross shape.

4. The flexible conformal passive sensor based on spiral microstructure metamaterial according to claim 1, characterized in that: The point defect structure includes a second cubic block and four spiral microstructures. The four spiral microstructures are respectively connected to the four side surfaces of the second cubic block, and the four spiral microstructures are arranged in a cross shape.

5. The flexible conformal passive sensor based on spiral microstructure metamaterial according to claim 1, characterized in that: The connecting ends between adjacent spiral microstructures are provided with connecting hemispheres as nodes.

6. The flexible conformal passive sensor based on spiral microstructure metamaterial according to claim 1, characterized in that: The piezoelectric material is disposed within a spiral microstructure connected to the second cubic block.

7. The flexible conformal passive sensor based on spiral microstructure metamaterial according to claim 1, characterized in that: The axis equation of the spiral microstructure includes an ideal spiral line equation of the middle section and transition joint curve equations at both ends.

8. A design method for a flexible conformal passive sensor based on spiral microstructure metamaterial, characterized in that: include: Based on the axis equation of the spiral structure, a spiral microstructure is designed using metamaterials; Connecting a plurality of the spiral microstructures through the first cubic block as a connection point to design a unit cell structure; The unit cell structures are periodically arranged in a plane, and the connections between adjacent unit cell structures are formed by combining two connected hemispheres into a complete sphere as a node to design a three-dimensional structure; Replacing a first cubic block of the unit cell structure at the center of the three-dimensional structure with a second cubic block to obtain a point defect design of a finite period structure; A sensor, an energy storage element and a piezoelectric material are respectively installed on the first cubic block, the second cubic block and the spiral microstructure connected to the second cubic block, and the energy storage element is electrically connected to the sensor and the piezoelectric material respectively to obtain a passive sensor.

9. The method according to claim 8, characterized in that Based on the spiral structure axis equation, a spiral microstructure is designed using metamaterials, including: Establishing an ideal helix equation curve and adding transition joint curves at both ends of the ideal helix equation curve to obtain the helical structure axis equation; Based on the spiral structure axis equation and metamaterial, a spiral microstructure is designed by sweeping a circular surface.

10. The method according to claim 8, characterized in that Connecting a plurality of the spiral microstructures through the first cubic block as a connection point to design a unit cell structure includes: Taking the center of one end face of the spiral microstructure as the rotation center, the array is arranged at 90° intervals to obtain a cross-shaped structure; A first cubic block is established with the center position of the cross-shaped structure as the center, and connecting hemispheres are respectively established at the centers of the four circular cross sections outside the cross-shaped structure to obtain a unit cell structure.

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