Wearable fractal artificial surface plasmon transmission line based on embroidery technology

Abstract

The invention discloses a wearable fractal artificial surface plasmon transmission line based on an embroidery technology, which comprises the following steps: designing an artificial surface plasmon unit structure based on a fractal principle, and carrying out dispersion analysis on the artificial surface plasmon unit structure; based on dispersion analysis, the indentation depth and the indentation angle of the fractal artificial surface plasmon unit structure are determined, and normalized electric field analysis is carried out; according to the artificial surface plasmon unit structure, transmission line prototype design is carried out, and a fractal artificial surface plasmon transmission line real object is manufactured by using an embroidery technology; and carrying out real object performance test on the manufactured fractal artificial surface plasmon transmission line real object. Therefore, by the adoption of the method, the design is simple, cracking is not likely to happen, mechanical performance is stable, smaller transverse width and stricter field limiting capacity can be achieved, influences of human body proximity are avoided, and the method is more suitable for wearing application.

Description

Technical Field

[0001] The present invention relates to the field of intelligent wearable interconnection, and in particular to a wearable fractal artificial surface plasmon transmission line based on embroidery technology. Background Art

[0002] Smart clothing, also known as smart apparel or electronic textiles, is the product of the integration of modern technology and fashion design, representing the innovative application of wearable technology in the field of clothing. With the rapid development of cutting-edge technologies such as the Internet of Things, artificial intelligence, nanotechnology and biosensors, smart clothing, as an important manifestation of smart wearable technology, has attracted more and more attention. In addition, microelectronic devices, fiber materials and weaving technologies used in smart wearable systems have been well developed. However, how to build an interconnection system on the fabric, reliably connect the devices on the surface and inside the fabric to the system, and realize information transmission, communication networking and information reception and transmission still requires further research and development.

[0003] At present, in order to realize the interconnection function of smart clothing, scholars have conducted multi-faceted research and have developed three interconnection schemes: direct cable interconnection, wireless interconnection, and interconnection based on artificial surface plasmon (SSPP) fabric transmission lines.

[0004] Cable-based interconnection refers to the direct interconnection of components integrated into smart clothing with cables. This interconnection method is widely used in clinical and research environments to connect various sensor nodes. However, the difficulty with this connection method is that it interferes with the wearer's physical activities and is not suitable for continuous use.

[0005] Using antennas to achieve wireless access and interconnection of devices is another way to achieve interconnection of smart clothing. However, wireless interconnection methods require the transmission of radio waves to the surrounding space, which consumes a lot of energy and is easily intercepted by others. Therefore, wireless interconnection methods have high requirements for hardware and software, which limits the size, lifespan and function of body-based sensors.

[0006] In contrast to radio waves, electromagnetic waves at optical frequencies can be confined to metal surfaces in the form of localized excitations known as surface plasmons. Surface plasmons are widely used as interconnects in integrated photonic devices because they propagate consistently along the surface and interact strongly with nearby objects via evanescent fields. Although surface plasmons do not exist in natural materials at radio frequencies, these electromagnetic modes can be engineered through structured conductive surfaces. In addition, clothing with artificial surface plasmon fabric transmission line structures can support surface plasmon modes at communication frequencies, providing a platform for radio wave propagation around the body.

[0007] In summary, the surface plasmon mode approach enables the development of energy-efficient and secure wireless body sensor networks interconnected by radio surface plasmons propagating on artificial surface plasmon fabric transmission lines, and interconnection of devices is achieved through contactless proximity to the body without the need for "plugging in". In particular, when standard wireless devices are placed near the metamaterial textile, their interconnection is achieved through the propagation of wireless signals as surface waves, rather than through the radiation of wireless signals into the surrounding space, making personal sensor networks efficient, interference-free, and secure.

[0008] Most of the existing artificial surface plasmon transmission lines are attached to smart clothing by pasting conductive fabrics; although this preparation process is simple, it is prone to cracking, has unstable mechanical properties, and is not resistant to friction and washing. In addition, fabric-type artificial surface plasmon transmission lines can also be made using embroidery technology, but there is a problem of excessive lateral width.

[0009] Therefore, there is an urgent need for a fabric-type artificial surface plasmon transmission line with a small lateral width that is not affected by the proximity of the human body and is more suitable for wearable applications. Summary of the invention

[0010] The purpose of the present invention is to provide a wearable fractal artificial surface plasmon transmission line based on embroidery technology, which has a simple design, is not easy to crack, has stable mechanical properties, is not affected by the proximity of the human body, and is more suitable for wearable applications.

[0011] In order to achieve the above object, the present invention provides a wearable fractal artificial surface plasmon transmission line based on embroidery technology, comprising the following steps:

[0012] S1. Based on the fractal principle, design a fractal artificial surface plasmon unit structure and perform dispersion analysis on the fractal artificial surface plasmon unit structure;

[0013] S2. Perform normalized electric field analysis based on the dispersion analysis in step S1;

[0014] S3. Design a transmission line prototype based on the fractal artificial surface plasmon unit structure, and use embroidery technology to make a physical fractal artificial surface plasmon transmission line;

[0015] S4. Conduct physical performance tests on the fabricated fractal artificial surface plasmon transmission line.

[0016] Preferably, in step S1, the design of the fractal artificial surface plasmon unit structure model includes determining the open strip length and width, the microstrip line width, and the period length.

[0017] Preferably, in step S2, the dispersion analysis includes: determining the indentation depth and the indentation angle by means of equal area constraint.

[0018] Preferably, in step S3, the transmission line prototype design includes adopting a conical periodic structure and manufacturing a physical object of a fractal artificial surface plasmon transmission line according to an embroidery process.

[0019] Preferably, the embroidery process includes using wilcom plate-making software to design a transmission line prototype, making the transmission line prototype by a computer embroidery machine, loading an isolation layer and a ground layer, and welding an SMA connector to obtain a fractal artificial surface plasmon transmission line object.

[0020] Preferably, in step S4, the physical performance test includes: performing free space testing, testing on different parts of the human body, and human body specific absorption rate verification testing on the physical fractal artificial surface plasmon transmission line to verify the feasibility of the embroidery smart wearable transmission line.

[0021] Therefore, the present invention adopts the above-mentioned wearable fractal artificial surface plasmon transmission line based on embroidery technology, which has the following technical effects:

[0022] (1) Based on embroidery technology, artificial surface plasmon transmission lines are designed and manufactured, which are simple in design, not easy to crack, and have stable mechanical properties;

[0023] (2) The use of fractal technology to design artificial surface plasmon structures can achieve smaller lateral width and stricter field confinement capabilities, and is not affected by the proximity of the human body, making it more suitable for wearable applications.

[0024] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of a surface plasmon unit model in an embodiment of a wearable fractal artificial surface plasmon transmission line based on embroidery technology. Figure 1 (a) is the traditional surface plasmon unit model. Figure 1 (b) is the Minkowski fractal surface plasmon unit model. Figure 1 (c) is the Koch fractal artificial surface plasmon unit model;

[0026] Figure 2 is a dispersion curve diagram of different strip lengths in an embodiment of a wearable fractal artificial surface plasmon transmission line based on embroidery technology;

[0027] Figure 3 It is a dispersion curve diagram of the change of different indentation depths ω of the Minkowski fractal in an embodiment of a wearable fractal artificial surface plasmon transmission line based on embroidery technology;

[0028] Figure 4It is a dispersion curve diagram of the Koch fractal with different indentation angles θ in an embodiment of a wearable fractal artificial surface plasmon transmission line based on embroidery technology;

[0029] Figure 5 It is a normalized electric field analysis of three structural types in an embodiment of a wearable fractal artificial surface plasmon transmission line based on embroidery technology;

[0030] Figure 6 It is a schematic diagram of the design of three intelligent wearable transmission lines in the embodiment of a wearable fractal artificial surface plasmon transmission line based on embroidery technology. Figure 6 (a) is a traditional transmission line configuration. Figure 6 (b) is a Minkowski type transmission line configuration. Figure 6 Middle (c) is the Koch fractal transmission line configuration;

[0031] Figure 7 It is a schematic diagram of the forming process of an embroidery transmission line in an embodiment of a wearable fractal artificial surface plasmon transmission line based on embroidery technology;

[0032] Figure 8 It is a wearable fractal artificial surface plasmon transmission line based on embroidery technology. The three kinds of smart wearable transmission lines in the embodiment are real pictures;

[0033] Fig. 9 This is a simulation test result diagram of a smart wearable transmission line in an embodiment of a wearable fractal artificial surface plasmon transmission line based on embroidery technology. Fig. 9 (a) is the traditional type. Fig. 9 (b) is the Minkowski type, Fig. 9 (c) is the Koch fractal type;

[0034] Fig.10 This is a schematic diagram of testing different positions of the human body in an embodiment of a wearable fractal artificial surface plasmon transmission line based on embroidery technology. Fig.10 (a) in the middle is the chest, Fig.10 Middle (b) is the forearm area. Fig.10 (c) Thigh area;

[0035] Fig.11 This is a test result diagram of different positions of the human body in an embodiment of a wearable fractal artificial surface plasmon transmission line based on embroidery technology. Fig.11 (a) is the traditional type. Fig.11 (b) Minkowski type, Fig.11 (c) is the Koch fractal type;

[0036] Fig.12It is a schematic diagram of a simulation environment-human tissue model in an embodiment of a wearable fractal artificial surface plasmon transmission line based on embroidery technology;

[0037] Fig.13 It is a wearable fractal artificial surface plasmon transmission line based on embroidery technology. In the embodiment, three kinds of intelligent wearable artificial surface plasmon transmission lines are shown in SAR simulation results. Fig.13 (a) is the traditional type. Fig.13 (b) Minkowski type, Fig.13 (c) is the Koch fractal type. DETAILED DESCRIPTION

[0038] The present invention can be explained in more detail by the following examples. The purpose of disclosing the present invention is to protect all changes and improvements within the scope of the present invention. The present invention is not limited to the following examples.

[0039] A wearable fractal artificial surface plasmon transmission line based on embroidery technology comprises the following steps:

[0040] S1, such as Figure 1 As shown, after determining the open strip length l = 27mm, width w = 2mm, and microstrip line width w m =1.5mm, period length p=12mm, based on the fractal principle, artificial surface plasmon unit structure.

[0041] In this embodiment, based on the Minkowski fractal and Koch fractal principles, a Minkowski artificial surface plasmon unit structure and a Koch fractal artificial surface plasmon unit structure were established, and a traditional artificial surface plasmon unit structure was established as a control group for analysis.

[0042] In order to increase field confinement and localization, the most effective method is to extend the open band length. By analyzing the dispersion of the artificial surface plasmon unit structure, the dispersion curves of different open band lengths l are compared, such as Figure 2 As l increases, the dispersion curve is effectively depressed, the slow wave effect is obvious, and it is more conducive to field confinement; but it brings the disadvantage of increasing the open band length (i.e., the lateral width), which is not desirable in a compact system.

[0043] In order to overcome the disadvantage of increased lateral width, this embodiment uses a fractal structure to design artificial surface plasmons, such as Figure 1 (a) and Figure 1As shown in (b). For the two fractal structures, they can be compared from two directions, namely, equal length constraint and equal area constraint. In order to determine which fractal method is more effective, this embodiment adopts equal area constraint. First, the length of the open band is determined to be l = 27mm, that is, the lateral width. When the equal area constraint is found, the fractal length is the largest, and the structural period p = 12mm is determined; when the lateral width is equal and the unit period is determined, since the size of the unit structure is determined, the indentation depth and indentation angle under the Minkowski fractal and Koch fractal methods can be obtained by calculation.

[0044] Among them, when the equal area constraint is used, for Minkowski and Koch fractals, the relationship between the indentation depth and the indentation angle is as follows:

[0045]

[0046] Where ω is the indentation depth and n is the indentation angle.

[0047] against Figure 1 The structure uses the parameters determined above and sets the microstrip line width w m =1.5mm, the dispersion curve of the Minkowski fractal structure changing with the indentation depth ω is obtained, as shown in Figure 3 As shown. Figure 3 It can be seen from the figure that when a fractal is performed, for the Minkowski fractal, the larger the indentation depth ω is, the lower the dispersion curve of the unit structure is pressed, and the more obvious the artificial surface plasmon effect is.

[0048] Where, the microstrip line width w is set m =1.5mm, a 50Ω microstrip line can be obtained, making the structure have low loss characteristics.

[0049] In addition, according to the above method, the dispersion curve of Koch fractal with the change of indentation angle θ is obtained, as shown in Figure 4 As shown. Figure 4 It can be seen that the larger the indentation angle θ is, the more obvious the dispersion effect is.

[0050] In summary, the dispersion curves of the Minkowski fractal structure and the Koch fractal structure will be depressed as the indentation depth or indentation angle increases, showing better artificial surface plasmon response.

[0051] S2. According to the dispersion analysis results, normalized electric field analysis is performed as follows:

[0052] According to the electric field analysis results, the normalized electric field size of the traditional artificial surface plasmon, Minkowski fractal and Koch fractal unit structure in the vertical direction in the cross section (xz plane) at 1.5 GHz is obtained, as shown in Figure 5As shown. It can be seen that at the same frequency, when deviating from the coordinate center, the two curves of the Minkowski fractal and Koch fractal unit structures will degenerate sharply, indicating that the artificial surface plasmon wave is tightly confined to the surface of the artificial surface plasmon unit. If the confinement area is defined as from the maximum electric field intensity to 1 / e, the fields of the Minkowski fractal and the Koch fractal are both confined to a smaller area than the traditional artificial surface plasmon; among them, the field confinement range of the Koch fractal is reduced from 4.43mm to 2.23mm, a reduction of about 49.7%; the field confinement range of the Minkowski fractal is reduced from 4.43mm to 1.47mm, a reduction of about 66.8%, and the field confinement capability of the Minkowski fractal is stronger than that of the Koch fractal.

[0053] In summary, both Minkowski fractal and Koch fractal artificial surface plasmon structures can play the role of near-field enhancement and solve the problem of lateral width constraints.

[0054] S3. Based on the three intelligent wearable artificial surface plasmon unit structures designed by the above analysis, the transmission line is designed, and the transmission line is physically manufactured according to the embroidery technical process, as follows:

[0055] According to the analysis of the dispersion characteristics of the unit structure, three types of smart wearable artificial surface plasmon transmission lines are designed using a conical periodic structure. Their geometric configurations are as follows: Figure 6 shown.

[0056] Among them, the configurations of the traditional wearable artificial surface plasmon transmission line, the Minkowski fractal artificial surface plasmon transmission line, and the Koch fractal artificial surface plasmon transmission line are as follows: Figure 6 Middle (a), Figure 6 Middle (b), Figure 6 As shown in (c), the lateral widths of the designed traditional wearable artificial surface plasmon transmission line, Minkowski fractal artificial surface plasmon transmission line and Koch fractal artificial surface plasmon transmission line are all 27 mm; but the cutoff frequency of the traditional wearable artificial surface plasmon transmission line is 2.25 GHz, the cutoff frequency of the Minkowski fractal artificial surface plasmon transmission line is 1.56 GHz, and the cutoff frequency of the Koch fractal artificial surface plasmon transmission line is 1.84 GHz.

[0057] From the dispersion fractal of the unit, it can be seen that for the Minkowski fractal artificial surface plasmon transmission line, when the cutoff frequency reaches 1.56GHz, combined with Figure 2It can be seen that the traditional artificial surface plasmon transmission line can only reach this frequency when the length is 39mm, so the lateral width of the Minkowski fractal artificial surface plasmon transmission line is 69.2% of the lateral width of the traditional artificial surface plasmon transmission line, which is reduced by 30.8%; for the Koch fractal artificial surface plasmon transmission line, when the cutoff frequency reaches 1.84GHz, the traditional artificial surface plasmon transmission line can only reach this frequency when the length is 33mm, so the lateral width of the Koch fractal artificial surface plasmon transmission line is 81.8% of the lateral width of the traditional artificial surface plasmon transmission line, which is reduced by 18.2%. It can be seen that under the condition of equal length, the Minkowski fractal and the Koch fractal are constrained to have equal areas, and the Minkowski fractal artificial surface plasmon transmission line is more conducive to reducing the lateral width of the transmission line, and is more conducive to the miniaturization of microwave plasma components.

[0058] Based on the schematic configuration parameters of the above-mentioned smart wearable artificial surface plasmon transmission line, combined with HFSS simulation analysis, according to Figure 7 Embroidery transfer line forming process Three types of transfer line prototypes were produced, such as Figure 8 shown.

[0059] S4. Conduct physical performance tests on the manufactured transmission lines, mainly including free space tests, tests on different parts of the human body, and verification of the human body's specific absorption rate.

[0060] (1) Free space test

[0061] According to the above-designed and produced artificial surface plasmon transmission line prototype of smart wearable embroidery technology, free space test was carried out by network analyzer, and the simulated free space test results of three types of smart wearable transmission lines, namely traditional type, Minkowski type and Koch fractal type, were obtained, as shown in Figure 2. Fig. 9 As shown. Fig. 9 As can be seen in Figure 1, the simulation results are in good agreement with the measured results. However, the test results have higher losses, which are due to the 5Ω / mm impedance of the embroidery transmission line, the unevenness of the embroidery conductive surface, and the connection loss when the SMA connector is connected to the flexible transmission line.

[0062] (2) Testing on different parts of the human body

[0063] Since the artificial surface plasmon fractal transmission line is a smart wearable transmission line, in practical applications, the structure of the transmission line may change due to changes in human posture, which may lead to changes in performance. Therefore, the performance of the prototype of the smart wearable artificial surface plasmon transmission line under human body load is analyzed. Fig.10 As shown, the embroidery artificial surface plasmon transmission lines are installed on different parts of the human body (i.e., chest, forearm and thigh), wherein transparent tape is used to fix the transmission lines on different positions of the human body. Fig.10 (a) is placed parallel to the chest. Fig.10 (b) is placed parallel to the forearm with a bending radius of 42.9 mm. Fig.10 The middle (c) is placed parallel to the thigh with a bending radius of 76.4 mm.

[0064] against Fig.10 The S parameter test was carried out on the different installation positions shown in the figure. The test results are shown in Fig.11 As shown. Fig.11 It can be seen that when installed on different parts of the body, the S parameter results remain almost unchanged, and the free space and chest test results are almost the same. Fig.10 Medium S 21 The change of (insertion loss of transmission line) is more obvious, and it will also change slightly with the bending degree of the test part, but the change of its loss value is within a reasonable range. Therefore, the fractal artificial surface plasmon transmission line made based on embroidery technology is not affected by the proximity of the human body and is insensitive to the curvature of the transmission line. It is a good preparation method for smart wearable devices.

[0065] (3) Human body specific absorption rate SAR test

[0066] Since the electromagnetic radiation generated by smart wearable devices is harmful to the human body, a safety assessment is needed. The human body specific absorption rate of three types of smart wearable embroidery artificial surface plasmon transmission lines was studied. The transmission lines were placed 1mm above the human tissue model for SAR simulation. Fig.12 As shown. Under an incident power of 1W, the 10-gSAR of the traditional wearable artificial surface plasmon transmission line, the Minkowski fractal artificial surface plasmon transmission line, and the Koch fractal artificial surface plasmon transmission line at 1.5GHz are 0.573W / kg, 0.417W / kg, and 0.460W / kg, respectively. Fig.12 As shown in the figure. Since the YD / T 1644 standard stipulates that 10-gSAR cannot exceed 2W / kg, the SAR values ​​of the above three smart wearable embroidery artificial surface plasmon transmission lines are significantly lower than the YD / T standard. Therefore, the electromagnetic radiation generated by the fractal artificial surface plasmon transmission line made based on embroidery technology will not cause harm to the human body and meet the requirements for safe use.

[0067] Therefore, the present invention adopts the above-mentioned wearable fractal artificial surface plasmon transmission line based on embroidery technology, which can achieve smaller lateral width, stricter field limitation capability, simple design, not easy to crack, stable mechanical properties; and is not affected by the proximity of the human body, and is more suitable for wearable applications.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A wearable fractal artificial surface plasmon transmission line based on embroidery technology, characterized in that: The following steps are involved: S1. Based on the fractal principle, design a fractal artificial surface plasmon unit structure and perform dispersion analysis on the fractal artificial surface plasmon unit structure; S2. Perform normalized electric field analysis based on the dispersion analysis in step S1; S3. Design a transmission line prototype based on the fractal artificial surface plasmon unit structure, and use embroidery technology to make a physical fractal artificial surface plasmon transmission line; S4. Conduct physical performance tests on the fabricated fractal artificial surface plasmon transmission line.

2. According to claim 1, a wearable fractal artificial surface plasmon transmission line based on embroidery technology is characterized in that: In step S1, the design of the fractal artificial surface plasmon unit structure model includes determining the open strip length and width, the microstrip line width, and the period length.

3. The wearable fractal artificial surface plasmon transmission line based on embroidery technology according to claim 1, characterized in that: In step S2, the dispersion analysis includes determining the indentation depth and the indentation angle through equal area constraints.

4. The wearable fractal artificial surface plasmon transmission line based on embroidery technology according to claim 1, characterized in that: In step S3, the transmission line prototype design includes using a conical periodic structure to produce a fractal artificial surface plasmon transmission line object according to an embroidery process.

5. The wearable fractal artificial surface plasmon transmission line based on embroidery technology according to claim 4, characterized in that: The embroidery process includes using wilcom plate-making software to design the transmission line prototype, using a computer embroidery machine to make the transmission line prototype, loading the isolation layer and the ground layer, and welding the SMA connector to obtain the actual fractal artificial surface plasmon transmission line.

6. The wearable fractal artificial surface plasmon transmission line based on embroidery technology according to claim 1, characterized in that: In step S4, the physical performance test includes: performing free space test on the physical fractal artificial surface plasmon transmission line, testing on different parts of the human body, and verifying the specific absorption rate of the human body to verify the feasibility of the embroidery smart wearable transmission line.

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