Flexible graphene RFID ear tag antenna based on information-based livestock management and application

Abstract

The application discloses a flexible graphene RFID ear tag antenna based on informationized livestock management, which comprises a substrate, a tag antenna and a radio frequency identification chip; the tag antenna comprises a symmetric loop dipole with double radiation arms bent inward, a feeding structure based on T-shaped matching and a complete circular ring located at the inner side; the tag antenna and the radio frequency identification chip are arranged on the substrate; the symmetric loop dipole with double radiation arms bent inward comprises an outer ring and an inner ring; the connecting line between the center point of the interval distance between the symmetric loop dipole arms and the center point of the loop is a symmetric line; the feeding structure based on T-shaped matching is symmetrically arranged along the symmetric line at the intersection point of the symmetric line and the outer ring to form a short-circuit branch; and the intersection point is connected with the radio frequency identification chip as a feeding port. The application can be used for informationized livestock management and has the characteristics of miniaturization, light weight, flexibility and corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of technology, and in particular to a flexible graphene RFID ear tag antenna based on information-based livestock management and its application. Background Technology

[0002] In an information-based livestock farming system, the collection and identification of individual livestock data are prerequisites for building a complete information chain and a fundamental link for realizing key functions such as precision feeding, behavior monitoring, disease early warning, and traceability management. Therefore, livestock identification and communication devices that are highly stable, reliable, and wearable for extended periods play an irreplaceable role in the construction of smart farms.

[0003] UHF RFID electronic ear tags have become the mainstream solution for livestock identification due to their advantages such as non-contact identification, long reading and writing distance, strong resistance to contamination, and rapid batch identification. However, existing electronic ear tags generally use metal materials as antenna conductors. The high density and rigidity of metal, coupled with a less-than-ideal electromagnetic structure design, result in large overall size, heavy weight, and lack of flexibility, making it difficult to adapt to the natural bending and long-term movement of livestock ears. Furthermore, these traditional antenna materials are prone to corrosion in complex livestock environments such as sweat and urine, leading to performance degradation. Long-term wear may result in shortened identification distance, decreased reading and writing stability, or even structural breakage. Moreover, excessive weight or high rigidity of the ear tags can cause discomfort to livestock, inducing stress reactions, ear friction damage, and even fighting, thus affecting livestock safety and management effectiveness.

[0004] Therefore, there is an urgent need to develop a new type of RFID ear tag antenna that is miniaturized, lightweight, flexible, resistant to corrosion in livestock environments, and can maintain stable radio frequency performance. Summary of the Invention

[0005] To improve the lifespan and recognition reliability of electronic ear tags in practical livestock applications and promote the continuous development of information-based livestock management, this invention provides a flexible graphene RFID ear tag antenna based on information-based livestock management, employing the following technical solution:

[0006] In a first aspect, the present invention provides a flexible graphene RFID ear tag antenna based on information-based livestock management, including a substrate, a tag antenna, and a radio frequency identification chip; the tag antenna includes a symmetrical ring dipole with double radiating arms bent inward, a feeding structure based on T-type matching, and a complete ring located on the inner side.

[0007] The tag antenna and the radio frequency identification chip are both disposed on the substrate;

[0008] The symmetrical annular dipole arm with inward bending of the double-radiating arms includes an outer ring and an inner ring. The line connecting the center point of the spacing distance between the symmetrical annular dipole arms with inward bending of the double-radiating arms and the center point of the ring is a symmetry line. At the intersection of the symmetry line and the outer ring, a feed structure based on T-type matching is symmetrically arranged along the symmetry line to form a short-circuit stub. The intersection point serves as a feed port connected to the radio frequency identification chip.

[0009] In some possible implementations, the outer ring, the inner ring, and the complete ring are concentric structures.

[0010] In some possible implementations, the T-shaped matching feed structure formed by symmetrically setting a short-circuit stub at the intersection of the symmetry line and the outer ring specifically includes: adding a feed line at the intersection, i.e., the middle position of the symmetrical ring dipole, to form a short-circuit stub, which together with the symmetrical ring dipole forms a feed coil. The feed part of the symmetrical ring dipole is a T-shaped matching structure formed with the central short-circuit feed line, and the short-circuit feed line is recessed towards the outer ring.

[0011] In some possible implementations, the RFID chip is an Impinj M730 with an impedance of 9.95-j166.65 at 915 MHz, which is directly connected to both ends of the feeder.

[0012] In some possible implementations, the tag antenna has a radius of 13 mm, the complete circular ring has a radius of 9.07 mm and a width of 1.3 mm, the distance between the two ends of the feed line is 0.2 mm, the width of the recessed groove is 2.4 mm, the width of the short-circuited stub is 0.8 mm, the distance between the outer ring and the inner ring is 1.4 mm, the distance between the inner ring and the complete circular ring is 0.4 mm, and the spacing between the symmetrical annular dipole arms is 0.4 mm.

[0013] In some possible implementations, the substrate material is polyethylene terephthalate, i.e., PET.

[0014] In some possible implementations, the conductor material used in the tag antenna is graphene, or GAF.

[0015] Secondly, the present invention also provides an application of a flexible graphene RFID ear tag antenna for information-based livestock management. Based on the flexible graphene RFID ear tag antenna for information-based livestock management described in the first aspect, it is worn on livestock for data collection and identification.

[0016] This invention provides a flexible graphene RFID ear tag antenna for information-based livestock management and its application. Based on the high conductivity, lightweight, flexibility, and corrosion resistance of graphene, graphene is selected as the conductor material for the tag antenna. Combined with the unique tag antenna structure provided by this invention, a flexible graphene RFID ear tag antenna suitable for information-based livestock management is obtained. Compared with existing technologies, it has the following advantages:

[0017] 1. This invention does not rely on any additional matching networks, and the power transmission efficiency between the tag antenna and the chip reaches 99.81%;

[0018] 2. The tag antenna of the present invention has a small size and low profile, with the radiating part having a size of only π×(0.039λ0). 2 ×0.000315λ0 (λ0 is the wavelength of the free space wave at 900MHz);

[0019] 3. The effective reading range coefficient per unit area of ​​the tag antenna of this invention is 7.74 × 10⁻⁶. -3 m / mm 2 It is up to 3.873 times larger than tag antennas with the same reading range;

[0020] 4. The flexible graphene tag antenna easily conforms to the surface of various animal tissues. Compared with other metal tag antennas, the mechanical durability and chemical stability of this invention are superior. In terms of mechanical durability, it exhibits performance unaffected by 1000 repeated bending cycles. In terms of chemical stability, it shows no corrosion after 72 hours in 5% hydrogen chloride solution, 5% sodium hydroxide solution, and salt spray environment. Attached Figure Description

[0021] Figure 1 The tag antenna structure diagram provided by this invention;

[0022] Figure 2 A flowchart of the tag antenna design provided for this invention;

[0023] Figure 3 The current distribution diagram of the tag antenna provided by this invention at 915MHz;

[0024] Figure 4 The current distribution diagram of the tag antenna at 915MHz when L1=1mm is provided by the present invention;

[0025] Figure 5 A parameter analysis diagram showing the effect of the spacing F on the antenna impedance provided by this invention;

[0026] Figure 6 A before-and-after structural comparison diagram is introduced for the T-type matching provided by this invention;

[0027] Figure 7The present invention provides an impedance comparison analysis diagram before and after the introduction of T-type matching;

[0028] Figure 8 The parameter analysis diagram of the effect of S on antenna impedance provided by the present invention;

[0029] Figure 9 The parameter analysis diagram of the effect of M1 on antenna impedance provided by the present invention;

[0030] Figure 10 The parameter analysis diagram of the effect of M2 on antenna impedance provided by the present invention;

[0031] Figure 11 A comparison diagram of antenna impedance before and after adding the inner complete circular ring provided by the present invention;

[0032] Figure 12 The parameter analysis diagram of the effect of L2 on antenna impedance provided by the present invention;

[0033] Figure 13 Impedance diagram of the chip and tag antenna provided by this invention at 915MHz;

[0034] Figure 14 Various test schematic diagrams provided for this invention: (a) bending resistance test experiment; (b) 5% hydrogen chloride solution; (c) 5% sodium hydroxide solution; (d) salt spray test experiment;

[0035] Figure 15 This is a schematic diagram illustrating the theoretical reading distance of unprocessed and tested tags provided by the present invention.

[0036] In the diagram, 1-1 is a ring dipole, 1-2 is a tag antenna substrate, 1-3 is a complete circular ring, 1-4 is a T-type matched feed structure, and 1-5 is an RF chip. Detailed Implementation

[0037] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] Example 1

[0039] This embodiment provides a flexible graphene RFID ear tag antenna based on information-based livestock management, including a substrate, a tag antenna, and a radio frequency identification chip; the tag antenna includes a symmetrical ring dipole with double radiating arms bent inward, a feeding structure based on T-type matching, and a complete ring located on the inner side.

[0040] The tag antenna and RFID chip are both mounted on the substrate, such as Figure 1 As shown, the substrate material is polyethylene terephthalate (PET), with a thickness h of 0.08 mm. The conductor material used in the tag antenna is graphene (GAF), with a thickness z of 0.025 mm and an electrical conductivity of approximately 1.25 × 10⁻⁶ mm. 6 S / m, material density is approximately 1.73 g / cm³ 3 It has excellent conductivity and is lightweight, flexible, and corrosion resistant. Graphene-based tag antennas can achieve miniaturization, long reading distance, high flexibility, and good resistance to corrosion from sweat, urine, and other livestock environments. They will not cause discomfort or stress to livestock when worn, making them very suitable as electronic ear tags for information-based livestock management scenarios.

[0041] The RFID chip is an Impinj M730, with an impedance of 9.95-j166.65 at 915 MHz, directly connected to both ends of the feed line; the tag antenna radius R2 is 13mm, the complete ring radius R1 is 9.07mm and the width R is 1.3mm, the distance M between the two ends of the feed line is 0.2mm, the groove width M1 is 2.4mm, the short-circuit stub width M2 is 0.8mm, the distance L1 between the outer ring and the inner ring is 1.4mm, the distance L2 between the inner ring and the complete ring is 0.4mm, and the spacing F between the symmetrical annular dipole arms is 0.4mm; adding the complete ring allows for impedance adjustment without affecting antenna radiation.

[0042] like Figure 2 As shown, the symmetrical annular dipole arm with inward bending of the double-radiating arms includes an outer ring and an inner ring, which are the main radiating arms of the tag antenna; the outer ring, the inner ring, and the complete circular ring are concentric structures; the line connecting the center point of the spacing between the symmetrical annular dipole arms with inward bending of the double-radiating arms and the center point of the ring is the line of symmetry, and a T-type matching-based feed structure is symmetrically arranged along the line of symmetry at the intersection of the line of symmetry and the outer ring to form a short-circuit stub, and the intersection serves as a feed port for connecting the RFID chip; as shown Figure 2 The design process of the label antenna is completed in the order of (a), (b) and (c). (a) A symmetrical ring dipole with double radiating arms bent inward; (b) Introducing a feed structure based on T-type matching; (c) Adding a complete circular ring on the inner side.

[0043] Symmetrical ring dipole arms are the primary source of antenna radiation modes, such as Figure 3 As shown, the main current is concentrated in the inner ring and distributed along the two arms, which is the main source of the antenna's radiation mode. The inward bending design of the double radiating arms effectively extends the current path, significantly increases the equivalent electrical length of the antenna, and reduces the radius of the tag to one-twenty-fifth of the wavelength at 915MHz, achieving the goal of tag miniaturization, while also introducing a capacitance effect.

[0044] At the intersection of the symmetry line and the outer ring, a short-circuit stub is formed by symmetrically setting a feed structure based on T-type matching along the symmetry line. Specifically, this includes adding a feed line at the intersection point, i.e., the middle position of the symmetrical ring dipole, to form a short-circuit stub, which together with the symmetrical ring dipole forms a feed coil. The feed part of the symmetrical ring dipole is a T-type matching structure formed by matching the central short-circuit feed line. The short-circuit feed line is concave towards the outer ring, which has the effect of enhancing the inductance effect.

[0045] In this embodiment, as Figure 4 As shown, the bending width L1 of the dipole affects the mutual coupling between currents on the radiating arm; the closer the distance, the greater the loss of gain due to mutual coupling. Figure 5 As shown, the spacing F between the symmetrical ring dipole arms affects the resonant frequency of the antenna; the greater the spacing, the higher the resonant frequency. Figure 6 As shown, the antenna feed point is moved from the center of the original ring dipole to the center of the short-circuited feed line. The matching structure is equivalent to an impedance transformer, which indents the short-circuited feed line towards the ring dipole, thus enhancing the inductive effect. Figure 7 As shown.

[0046] By adjusting the slot width S between the T-match and the ring dipole radiating arm, the recessed groove width M1, and the short-circuit stub width M2, a larger impedance can be achieved under small size conditions; where, the larger S is, the smaller the antenna impedance; the larger M1 is, the larger the antenna impedance; and the smaller M2 is, the larger the antenna impedance. For example... Figure 8 , 9 As shown in Figure 10.

[0047] In this embodiment, the inner complete ring is a branch that can generate induced current, which helps with the impedance matching of the antenna, but does not participate in the antenna's radiation mode.

[0048] like Figure 11 As shown, after adding the inner complete circular ring, the resonant frequency decreases. After adding the ring, the impedance curve does not change in a fixed trend, but shifts forward as a whole, meaning the current distribution remains unchanged, but impedance matching is achieved. Therefore, adding the inner complete circular ring can adjust the impedance without affecting the antenna radiation effect. The distance L2 between the inner ring and the inner complete circular ring affects the generation of induced current, thus affecting the change of resonant frequency.

[0049] like Figure 12 As shown, the larger L2 is, the lower the resonant frequency shifts, and the impedance curve shows a shifting trend. This also means that the addition of a complete circular ring can adjust the impedance without affecting the antenna radiation.

[0050] Tag power transfer factor ( This is used to characterize the energy coupling efficiency between the chip and the antenna, and its definition is as follows:

[0051]

[0052] in, and These represent the complex impedances of the antenna and the chip, respectively. A higher power transfer coefficient means a more ideal impedance matching between the antenna and the chip, and more efficient energy transfer.

[0053] Based on the above, the tag antenna in this embodiment has a radius of 13mm, a maximum readout distance of 4.11m, and uses the Impinj M730 chip, which is directly connected to both ends of the feed line. The impedance of the tag antenna is approximately 10.84 + j166.35. A laser engraving machine is used to carve the center gap of the feed line (M = 0.2mm) to fit the selected chip. This chip has an impedance of 9.95 - j166.65 at 915MHz and a readout sensitivity of -24dBm. The impedance relationship between the chip and the tag antenna is as follows: Figure 13 As shown, the power transmission efficiency reaches 99.81%.

[0054] Therefore, the graphene flexible RFID tag antenna designed in this embodiment has significant advantages in miniaturization and long reading distance, and has stable ultra-high frequency (UHF) band operation capability, which can meet the comprehensive requirements of reliability, comfort and environmental adaptability of electronic ear tags for livestock (such as pigs) in information-based livestock management.

[0055] Example 2

[0056] This embodiment provides an application of a flexible graphene RFID ear tag antenna for information-based livestock management. Based on the flexible graphene RFID ear tag antenna for information-based livestock management in Embodiment 1, the flexible graphene RFID ear tag antenna is applied to information-based livestock management.

[0057] The tag antenna designed in Example 1 uses a highly conductive graphene film as the radiator material, which has excellent flexibility, sweat resistance, and corrosion resistance. It maintains a good fit when worn by livestock (such as pig ears), is less likely to trigger stress responses, and can effectively resist the erosion of complex chemicals in the livestock environment, such as bodily fluids. In this example, when the tag antenna was worn on livestock for data collection and identification, its flexibility and physical and chemical stability in the livestock environment were tested and verified.

[0058] The performance of the ear tag antenna in Example 1 was tested using the following method:

[0059] Verification of flexibility, durability, and mechanical reliability: such as Figure 14As shown in (a), the antenna was cyclically bent using a motor-driven slide rail test platform. In the experiment, the slide rail speed was set to 5 mm / s, and the single bending angle was 0°→90°→0°. After 1000 bending cycles, the ear tag antenna resonant frequency drift was less than 0.5%, and the radiating structure was intact without cracks, detachment, or other mechanical damage. This indicates that Example 1 has excellent flexibility and mechanical stability and can withstand dynamic bending caused by the daily behavior of livestock for a long time without affecting the radio frequency performance.

[0060] Verification of chemical tolerance in livestock environments: Livestock body fluids (sweat, urine, etc.) can generally be considered solutions containing mineral ions, electrolytes, and organic molecules, with a pH value typically between 4.5 and 7.9. To provide a more comprehensive assessment, weathering tests were conducted in acidic, alkaline solutions and salt spray environments. Figure 14 As shown in (b), (c), and (d), during the test, three Examples 1 were tested using a 5% HCl solution (simulating an acidic environment), a 5% NaOH solution (simulating an alkaline environment), and a salt spray environment (simulating chloride ion corrosion in sweat). A periodic spraying method was used, spraying once every 30 minutes. Before and after spraying, Examples 1 were attached to the beaker wall and directly exposed to air without being sealed. After 72 hours, visual inspection and microscopic morphology observation showed that the antenna structure was intact, and there was no obvious corrosion, blistering, peeling, or geometric deformation on the surface, indicating that Examples 1 has good chemical stability and corrosion resistance.

[0061] After completing the verification of flexibility, durability, mechanical reliability, and chemical tolerance in livestock environments, the antenna performance was verified using the Voyantic Tagformance Pro wireless testing system (operating frequency band 800-1000MHz, equivalent isotropic radiated power 2WEIRP). The test results are as follows: Figure 15 As shown, in Example 1, the maximum reading distance reaches 4.11m, and the effective reading distance coefficient per unit area is 7.74×10. -3 m / mm 2 Furthermore, the read performance remained stable before and after the test, with no significant degradation.

[0062] The above results demonstrate the flexibility and resistance to livestock environments of this invention, maintaining stable electromagnetic performance and structural reliability even under harsh livestock conditions. Its excellent flexibility allows for greater comfort for livestock (such as pig ears) without triggering stress responses; its good corrosion resistance effectively resists the erosion of bodily fluids such as sweat and urine, improving the service life and reliability of the electronic ear tag. Therefore, this invention is highly suitable for long-term wearing scenarios such as electronic ear tags for livestock (such as pigs) in information-based livestock management.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flexible graphene RFID ear tag antenna based on information-based livestock management, characterized in that, It includes a substrate, a tag antenna, and a radio frequency identification chip; the tag antenna includes a symmetrical ring dipole with two radiating arms bent inward, a feed structure based on T-type matching, and a complete circular ring located on the inner side; The tag antenna and the radio frequency identification chip are both disposed on the substrate; The symmetrical ring dipole with inwardly bent double-radiating arms includes an outer ring and an inner ring. The line connecting the center point of the spacing distance between the symmetrical ring dipole arms of the symmetrical ring dipole with inwardly bent double-radiating arms and the center point of the ring is a symmetry line. At the intersection of the symmetry line and the outer ring, a feed structure based on T-type matching is symmetrically arranged along the symmetry line to form a short-circuit stub. The intersection serves as a feed port connected to the radio frequency identification chip. The outer ring, the inner ring, and the complete circular ring are concentric structures.

2. The flexible graphene RFID ear tag antenna based on information-based livestock management according to claim 1, characterized in that, The symmetrical arrangement of a T-shaped matching feed structure at the intersection of the symmetry line and the outer ring to form a short-circuit stub specifically includes: adding a feed line at the intersection, i.e., the middle position of the symmetrical ring dipole, to form a short-circuit stub, which together with the symmetrical ring dipole forms a feed coil. The feed part of the symmetrical ring dipole is a T-shaped matching structure formed by matching the central short-circuit feed line, and the short-circuit feed line is recessed towards the outer ring.

3. The flexible graphene RFID ear tag antenna based on information-based livestock management according to claim 1, characterized in that, The radio frequency identification chip is an Impinj M730, which has an impedance of 9.95-j166.65 at 915 MHz and is directly connected to both ends of the feeder.

4. The flexible graphene RFID ear tag antenna based on information-based livestock management according to claim 3, characterized in that, The tag antenna has a radius of 13mm, the complete circular ring has a radius of 9.07mm and a width of 1.3mm, the distance between the two ends of the feed line is 0.2mm, the width of the recessed groove is 2.4mm, the width of the short-circuited stub is 0.8mm, the distance between the outer ring and the inner ring is 1.4mm, the distance between the inner ring and the complete circular ring is 0.4mm, and the spacing between the symmetrical annular dipole arms is 0.4mm.

5. The flexible graphene RFID ear tag antenna based on information-based livestock management according to claim 1, characterized in that, The substrate material is polyethylene terephthalate.

6. The flexible graphene RFID ear tag antenna based on information-based livestock management according to claim 1, characterized in that, The conductor material used in the tag antenna is graphene.

7. An application of a flexible graphene RFID ear tag antenna for information-based livestock management, based on any one of claims 1-6, characterized in that, The flexible graphene RFID ear tag antenna is worn on livestock for data collection and identification.

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