Method for testing thickness of rfid tag with coupled antenna structure and application

Abstract

This invention relates to a thickness testing method for RFID tags using a coupled antenna structure and its application. The thickness testing method includes the following steps: 1) setting up an ultra-high frequency antenna and a metal circuit on both sides of the thickness of the object to be tested, forming an RFID tag with a coupled antenna structure; 2) using an RFID reader to transmit ultra-high frequency electromagnetic waves of a specific frequency to read the information of the RFID tag with the coupled antenna structure; 3) obtaining the maximum reading distance of the RFID tag with the coupled antenna structure at a specific frequency; 4) obtaining the corresponding maximum reading distance for thickness test objects of the same material but different thicknesses; 5) obtaining a linear relationship curve between the thickness of the object to be tested and the maximum reading distance of the RFID tag with the coupled antenna structure; 6) obtaining the thickness of the object to be tested corresponding to the maximum reading distance measured by the RFID reader from the linear relationship curve in step 5). This invention enables the RFID tag with the coupled antenna structure to function as a thickness sensor.

Description

Technical Field

[0001] This invention relates to the field of radio frequency identification (RFID) technology, and more specifically to a method for testing the thickness of RFID tags using a coupled antenna structure and its application in humidity detection. Background Technology

[0002] RFID (Radio Frequency Identification) tags are a non-contact automatic identification technology that communicates with readers via radio waves to read and write data. In existing technologies, RFID tag technology has been deeply integrated into many fields, such as real-time tracking of goods location in logistics and warehousing, anti-theft and smart settlement of goods in retail scenarios, production process monitoring and parts management in manufacturing, drug traceability and patient identification in the medical field, and non-stop toll collection and vehicle management in transportation systems. However, RFID tags have always been used only as a module for recording data.

[0003] In existing technologies, RFID tags also collaborate with various sensors to transmit data monitored by these sensors. For example, patent CN113723131B, entitled "An RFID Pipe Section Identification and Management System," discloses a thickness measurement data acquisition device including a thickness sensor, an automatic thickness data acquisition module, a mobile network communication module, and an RFID antenna module, as well as an RFID pipe section identification system including pipe sections, RFID tags, RFID reading and writing devices, and mobile terminal devices. The patent describes that the thickness of the dredged pipe section is measured by the thickness sensor and collected by the automatic thickness data acquisition module, and then the thickness data is transmitted to the RFID reading and writing device via the RFID antenna module and RFID tag. Thus, it is evident that the RFID tag, which collaborates with the sensor, also serves only as a data recording module.

[0004] In their research and experiments, the applicant of this patent application discovered that when an RFID tag is constructed by coupling a metal circuit with an ultra-high frequency antenna, and an RFID reader emits UHF (ultra-high frequency) electromagnetic waves (e.g., 860-960 MHz) for reading, the maximum reading distance of the RFID reader is affected by the vertical distance between the metal circuit and the ultra-high frequency antenna. Based on this experimental result, the applicant of this patent application creatively proposed a thickness testing method for RFID tags using a coupled antenna structure. In this way, the RFID tag not only functions as a data recording module but also as a thickness sensor.

[0005] Inspired by the use of graphene-coupled antenna structures to test the thickness of RFID tags, the applicant of this patent application has continued their in-depth research and creatively proposed applying the thickness testing method of RFID tags with coupled antenna structures to humidity-responsive shape memory polymer (SMP) materials to test the ambient humidity of the RFID tags. Thus, the combination of the coupled antenna structure RFID tag and the humidity-responsive shape memory polymer (SMP) material can also function as a humidity sensor.

[0006] Furthermore, considering important applications of humidity sensors, such as vaccine transport cases, vaccines are composed of sensitive biological materials. The World Health Organization (WHO) and national health authorities have established guidelines for vaccine storage and handling, requiring vaccines to be stored under specified temperature and humidity conditions to ensure their efficacy and safety. Therefore, vaccine transport cases need to be capable of accurately monitoring humidity to ensure the vaccine maintains its efficacy throughout storage and transportation. Thus, humidity sensors are installed inside vaccine transport cases. However, existing humidity sensors have the following drawbacks: 1. Accuracy may decrease under extreme humidity conditions (such as high humidity environments >95% RH); 2. Vaccines mostly require low-temperature transportation, which can affect humidity measurement results; 3. Slow response speed, unable to reflect rapid changes in environmental humidity in a timely manner; 4. Sensitive to airborne pollutants, affecting measurement accuracy; 5. Sensitive to vibration and shock, which may damage or affect humidity measurement results during transportation; 6. Data transmission delay, unable to transmit data in real time; 7. Lack of remote monitoring capabilities, unable to upload data to a monitoring platform in real time, affecting management efficiency.

[0007] However, the above-mentioned drawbacks of existing humidity sensors can be overcome by the humidity sensor proposed by the applicant of this patent application, which combines an RFID tag with a coupled antenna structure with a humidity-responsive shape memory polymer (SMP) material. Therefore, the applicant of this patent application has proposed a technical solution that combines the thickness testing method of an RFID tag with a coupled antenna structure with a humidity-responsive shape memory polymer (SMP) material and applies it to a vaccine transport box. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a thickness testing method for RFID tags using a coupled antenna structure, so that the RFID tag can act as a thickness sensor while recording data.

[0009] The technical solution of this invention is to provide a method for testing the thickness of RFID tags using a coupled antenna structure, comprising the following steps: 1) An ultra-high frequency antenna and a metal circuit are respectively set on both sides of the thickness test object. The ultra-high frequency antenna and the metal circuit are opposite each other with the thickness test object in between. The metal circuit includes a metal ring and a chip. The ultra-high frequency antenna and the metal circuit form an RFID tag with a coupled antenna structure. 2) Use an RFID reader to transmit ultra-high frequency electromagnetic waves to read the information of the RFID tag in the coupled antenna structure; 3) Gradually change the distance between the RFID reader and the thickness test object to obtain the maximum reading distance. During the process of changing the distance, keep the frequency of the RFID reader transmission the same. 4) Gradually change the thickness of the test object with the same material, and set up the same specification UHF antenna and metal circuit on both sides respectively. Then repeat steps 2) and 3) to obtain the maximum reading distance corresponding to different thicknesses; 5) After repeating the test multiple times in step 4), obtain a list or linear relationship curve showing the correspondence between the thickness of the test object and the maximum reading distance of the RFID tag with the coupled antenna structure; 6) Set up UHF antennas and metal circuits of the same specifications on both sides of any thickness test object of the same material, and repeat steps 2) and 3) to obtain the maximum reading distance. Obtain the thickness of the thickness test object corresponding to the current maximum reading distance from the list or linear relationship curve in step 5).

[0010] Compared with existing technologies, the thickness testing method of RFID tags using a coupled antenna structure in this invention has the following advantages: Through multiple experiments, it has been determined that when using an RFID tag with a coupled antenna structure and then employing an RFID reader to transmit ultra-high frequency electromagnetic waves to read the information of the RFID tag, the maximum reading distance of the RFID tag with the coupled antenna structure decreases as the distance between the ultra-high frequency antenna and the metal circuit increases. Therefore, the distance between the ultra-high frequency antenna and the metal circuit can be determined based on the maximum reading distance of the RFID tag with the coupled antenna structure, which is the thickness of the object being tested in this invention. Thus, the RFID tag with the coupled antenna structure can function as a thickness sensor. Furthermore, compared with existing thickness testing methods, the RFID tag with the coupled antenna structure also has a built-in data recording function, enabling timely recording of information about the tested material and thickness test data.

[0011] Using coupled RFID technology to measure the thickness of an object is a novel thickness detection method. This involves placing an ultra-high frequency antenna and a metal circuit on both sides of the object along its thickness direction. By monitoring changes in the signal strength, dielectric constant, or resonant frequency of the RFID tag, which in turn affects the reading distance of the RFID tag in the coupled antenna structure, the object's thickness is measured. This method offers advantages such as high precision, real-time monitoring, and intelligent management, and can be applied to fields such as industrial equipment wall thickness monitoring, tire wear detection, and coating thickness measurement.

[0012] As an improvement, the ultra-high frequency antenna includes a substrate and an antenna. The antenna is disposed on one side of the substrate, which is attached to one side of the thickness test object. The antenna is located between the substrate and the thickness test object, or the substrate is located between the antenna and the thickness test object. Using this method, placing the antenna on the substrate provides a stable electromagnetic wave transmission environment, ensuring signal stability and reliability, and also facilitates attaching the ultra-high frequency antenna to the thickness test object via the substrate.

[0013] As an improvement, a protective film is provided on the outer side of the UHF antenna. The protective film is attached to the UHF antenna, and the antenna is located between the protective film and the thickness test object, or between the protective film and the substrate. Using this method, the protective film can prevent the UHF antenna from suffering physical damage and from the adhesion of dust and dirt.

[0014] As an improvement, step 3-1) is added after step 3). Step 3-1) involves adjusting the relative position between the UHF antenna and the metal circuit, and then repeating steps 2) and 3) to obtain the maximum reading distance. The optimal coupling position is the relative position between the UHF antenna and the metal circuit when the RFID tag with the coupled antenna structure achieves the maximum reading distance. In step 4), the relative position between the UHF antenna and the metal circuit is also set to the optimal coupling position in step 3-1) on test objects of different thicknesses. Using this method, the UHF antenna and the metal circuit can achieve optimal radiation efficiency after coupling, thus enabling the RFID tag with the coupled antenna structure to achieve the maximum reading distance. Under UHF conditions (e.g., 860-960 MHz), the reading distance of the RFID tag with the coupled antenna structure is 1 to 15 meters.

[0015] As an improvement, steps 3-2) and 3-3) are added after step 3). Step 3-2) involves gradually changing the frequency of the ultra-high frequency electromagnetic waves emitted by the RFID reader, and then repeating steps 2) and 3) to obtain the maximum reading distance corresponding to different frequencies. Step 3-3) involves obtaining a list or linear relationship curve between the frequency of the ultra-high frequency electromagnetic waves emitted by the RFID reader and the maximum reading distance of the RFID tag with the coupled antenna structure under the same thickness conditions. In step 4), after each change in the thickness of the test object with the same material, steps 3-2) and 3-3) are repeated. Using this method, the maximum reading distance of RFID tags with coupled antenna structures at multiple different frequencies can be obtained on the same thickness test object, increasing the test data. Then, different thickness test objects can be used for testing. Switching the reading frequency of the RFID reader is much more convenient than changing the thickness test object, and all test objects with the same thickness can be tested, improving testing efficiency.

[0016] This invention also provides an application of a thickness testing method for RFID tags using a coupled antenna structure in humidity monitoring. The technical solution is to use the thickness testing method for RFID tags using a coupled antenna structure as described above, wherein the thickness testing object is a humidity-responsive shape memory polymer; after step 6), step 7) is added. Step 7) includes determining the humidity of the corresponding environment based on the relationship between the thickness of the humidity-responsive shape memory polymer and the change in ambient humidity after determining the thickness of the humidity-responsive shape memory polymer.

[0017] Compared with existing humidity alarm monitoring technologies, which are all based on humidity sensors to test humidity, the thickness testing method of RFID tags with coupled antenna structures proposed in this invention for humidity monitoring introduces a new concept. It utilizes some physical characteristics of RFID tags with coupled antenna structures for humidity monitoring. For real-time humidity monitoring, humidity sensors also need to be combined with Internet of Things (IoT) technology, i.e., RFID technology. However, in this invention, the RFID tags with coupled antenna structures also have the function of recording data, which means that they can be used as both a data recording module and a humidity sensor, combining the two functions into one.

[0018] This invention also provides an application of a thickness testing method for RFID tags using a coupled antenna structure in vaccine transport boxes. The technical solution involves employing the thickness testing method for RFID tags using a coupled antenna structure as described above. The thickness testing object is the box material of the vaccine transport box, which is composed of a humidity-responsive shape memory polymer and an inner and outer layer of insulation material. The ultra-high frequency antenna is disposed on the humidity-responsive shape memory polymer on the inner side of the vaccine transport box, and the metal circuit is disposed on the insulation material on the outer side of the vaccine transport box. The vaccine transport box also includes a data processing and analysis module and an alarm module. The RFID reader and the coupled antenna structure... The RFID tags of the coupled antenna structure together form a humidity monitoring module. The RFID reader obtains the maximum reading distance data of the RFID tags by reading the coupled antenna structure RFID tags, and transmits the maximum reading distance data to the data processing and analysis module. The data processing and analysis module is used to obtain the thickness of the humidity-responsive shape memory polymer based on the maximum reading distance, and then determine the humidity inside the vaccine transport box. The data processing and analysis module is equipped with a humidity threshold, and is also used to trigger the alarm module to issue an alarm when the humidity inside the vaccine transport box exceeds the humidity threshold.

[0019] Compared to existing technologies that use independent humidity sensors, this invention utilizes a thickness testing method for RFID tags with coupled antenna structures in vaccine transport boxes. By leveraging the physical characteristics of these tags, the humidity inside the transport box is monitored. As the humidity changes, the humidity-responsive shape memory polymer deforms, changing its thickness. This alters the reading distance of the RFID tag with the coupled antenna structure. The RFID reader can then determine if there is an abnormal humidity level inside the transport box by observing this change in reading distance. Thus, this invention can serve as a humidity monitoring module for vaccine transport boxes. The RFID tag with the coupled antenna structure can both store vaccine information (serving as a data management module) and provide timely feedback on extreme humidity levels within the transport box, ultimately triggering an alarm module, enabling real-time monitoring of the humidity inside the vaccine transport box.

[0020] As an improvement, the RFID reader / writer employs an RFID performance tester. This tester is used to determine the maximum reading distance of RFID tags with coupled antenna structures without altering the distance between the reader / writer and the vaccine transport box. To obtain the maximum reading distance of RFID tags with coupled antenna structures, changing the distance between the RFID reader / writer and the thickness test object typically involves moving the RFID tag with the coupled antenna structure, i.e., the thickness test object. However, in vaccine application scenarios, frequently moving the vaccine transport box is clearly inappropriate. Using this method, when testing the maximum reading distance of RFID tags with coupled antenna structures, it is not necessary to move the vaccine transport box. Simply bringing the RFID performance tester close to the RFID tag with the coupled antenna structure, i.e., the vaccine transport box, is sufficient. The RFID performance tester, based on international standards (such as ISO / IEC 18046-3, EPCglobal Class 1 Generation 2, etc.), can evaluate the maximum reading distance of RFID tags with coupled antenna structures by measuring parameters such as field strength and power.

[0021] As an improvement, the RFID reader is equipped with a minimum reading distance threshold. The RFID reader is positioned at this minimum reading distance threshold from the vaccine transport box to read information from the RFID tag with the coupled antenna structure. If the RFID reader cannot read the information from the RFID tag with the coupled antenna structure, it will trigger the alarm module to issue an alarm. Using this method, when testing the maximum reading distance of the RFID tag with the coupled antenna structure, the vaccine transport box does not need to be moved; the RFID reader only needs to be positioned at the minimum reading distance threshold to read the tag information. If the RFID reader can read the information from the RFID tag with the coupled antenna structure, it indicates that the thickness of the humidity-responsive shape memory polymer is within the normal range, and the humidity inside the vaccine transport box is acceptable. If the RFID reader cannot read the information from the RFID tag with the coupled antenna structure, it indicates that the thickness of the humidity-responsive shape memory polymer is too large, meaning the humidity inside the vaccine transport box is too high, and the alarm module will respond promptly. The minimum reading distance threshold is set based on the thickness of the humidity-responsive shape memory polymer, that is, the maximum reading distance of the RFID tag with the coupled antenna structure corresponding to the thickness of the humidity-responsive shape memory polymer when the extreme humidity threshold is reached inside the vaccine transport box.

[0022] As an improvement, the aforementioned ultra-high frequency antenna uses a carbon-based antenna. A carbon-based antenna, also known as an antenna made of carbon-based materials, includes one or more of carbon black, activated carbon, carbon nanotubes, fullerenes, porous carbon, and graphene. Due to the special application scenarios of vaccines and the harsh temperature and humidity conditions, antennas made of carbon-based materials have stable performance and minimal impact on the vaccine. Graphene, in particular, is more stable than metals and other currently known carbon-based materials. When placed inside the vaccine transport box, it will not affect the vaccine. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the test structure for the thickness testing method of RFID tags using a coupled antenna structure according to the present invention.

[0024] Figure 2(a) shows the test results of the reading distance of RFID tags with coupled antenna structure related to frequency under different thickness conditions, using corrugated paper as the thickness test object.

[0025] Figure 2(b) shows the test results of the reading distance of the RFID tag with coupled antenna structure related to the thickness of the test object when corrugated paper is used as the thickness test object at a frequency of 920Hz.

[0026] Figure 3(a) shows the test results of the reading distance of RFID tags with coupled antenna structure related to frequency under different thickness conditions, using 3M foam as the thickness test object.

[0027] Figure 3(b) shows the test results of the reading distance of the RFID tag with coupled antenna structure related to the thickness of the test object when using 3M foam as the thickness test object at a frequency of 920Hz.

[0028] Figure 4(a) shows the test results of the reading distance of RFID tags with coupled antenna structures as a frequency under different thickness conditions, using rubber as the thickness test object.

[0029] Figure 4(b) is a schematic diagram of the test results of the reading distance of the RFID tag with coupled antenna structure related to the thickness of the test object when rubber is used as the thickness test object at a frequency of 920Hz.

[0030] Figure 5 This is a schematic diagram of the test structure for the application of the thickness testing method of RFID tags using a coupled antenna structure in humidity monitoring.

[0031] Figure 6 This is a schematic diagram of the test structure for the application of the thickness testing method of RFID tags using a coupled antenna structure of the present invention on a vaccine transport box.

[0032] Figure 7This is a block diagram of a vaccine transport box according to the present invention.

[0033] Figure 8 This is another modular block diagram of the vaccine transport box of the present invention.

[0034] As shown in the figure: 1. Thickness test object, 2. UHF antenna, 3. Metal circuit, 4. Humidity-responsive shape memory polymer, 5. Thermal insulation material. Detailed Implementation

[0035] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements.

[0036] In the accompanying drawings, the thickness, size, and shape of the objects have been slightly exaggerated for illustrative purposes. The drawings are for illustrative purposes only and are not drawn to scale.

[0037] It should also be understood that the terms "comprising," "having," "including," and "containing," when used in this specification, indicate the presence of the stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or combinations thereof. Furthermore, when expressions such as "...at least one" appear after a list of listed features, they modify the entire listed feature, not individual elements in the list.

[0038] Example 1: The thickness testing method for RFID tags utilizing a coupled antenna structure of the present invention includes the following steps: 1) An ultra-high frequency antenna and a metal circuit are respectively set on two sides along the thickness direction of the thickness test object, with the ultra-high frequency antenna and the metal circuit facing each other across the thickness test object, such as... Figure 1 As shown, the metal circuit includes a metal ring and a chip, and the ultra-high frequency antenna and the metal circuit form an RFID tag with a coupled antenna structure; 2) Use an RFID reader to transmit ultra-high frequency electromagnetic waves to read the information of the RFID tag with the coupled antenna structure; 3) Gradually change the distance between the RFID reader and the thickness test object to obtain the maximum reading distance. During the process of changing the distance, keep the frequency of the RFID reader transmission the same. 3-1) Adjust the relative position between the UHF antenna and the metal circuit, and then repeat steps 2) and 3) to obtain the maximum reading distance. When the RFID tag with the coupled antenna structure obtains the maximum reading distance, the relative position between the UHF antenna and the metal circuit is the optimal coupling position. 3-2) Gradually change the frequency of the ultra-high frequency electromagnetic waves emitted by the RFID reader, and then repeat steps 2) and 3) to obtain the maximum reading distance corresponding to different frequencies; 3-3) After repeated testing in step 3-2), a linear relationship curve between the frequency of the ultra-high frequency electromagnetic wave emitted by the RFID reader and the maximum reading distance of the RFID tag with the coupled antenna structure is obtained under the same thickness conditions; 4) Gradually change the thickness of the test object using the same material, and set up UHF antennas and metal circuits of the same specifications on both sides. The relative positions between the UHF antennas and metal circuits are also set to the optimal coupling positions in step 3-1). Then repeat steps 2) and 3) to obtain the maximum reading distance for different thicknesses. Repeat steps 3-2) and 3-3 after each change in the thickness of the test object using the same material. 5) After repeated testing in step 4), a linear relationship curve between the thickness of the test object and the maximum reading distance of the RFID tag with the coupled antenna structure is obtained; 6) Set up an ultra-high frequency antenna and a metal circuit of the same specification on two sides of any thickness test object of the same material. The relative position between the ultra-high frequency antenna and the metal circuit is also set to the optimal coupling position in step 3-1). Repeat steps 2) and 3) to obtain the maximum reading distance. Obtain the thickness of the thickness test object corresponding to the current maximum reading distance from the linear relationship curve obtained in step 5).

[0039] In this embodiment, the chip is attached to the metal ring using conductive adhesive and flip-chip technology to form a metal circuit, which is also a metal inductor loop. The metal ring can be made of a single metal or an alloy, such as one or more of copper, gold, silver, aluminum, nickel, and copper-silver alloys; the chip can be R6p, H3, M750, U8, etc. In this embodiment, an aluminum ring and an R6P chip are used.

[0040] In this embodiment, the ultra-high frequency antenna includes a substrate and an antenna. The antenna is disposed on one side of the substrate, and the substrate is attached to one side of the thickness test object. The antenna is located between the substrate and the thickness test object. Alternatively, the substrate can be located between the antenna and the thickness test object, and a protective film can be disposed on the outside of the antenna, so that the antenna is located between the protective film and the substrate. The ultra-high frequency antenna is a carbon-based antenna, and the material of the carbon-based antenna includes one or more of carbon black, activated carbon, carbon nanotubes, fullerene, porous carbon, and graphene. In this embodiment, a graphene antenna is used. The graphene antenna can be fabricated using graphene ink screen printing / stencil printing / flexographic printing methods, laser etching of graphene film, or die-cutting of graphene film.

[0041] The working principle of coupling a metal circuit with an ultra-high frequency antenna can be briefly explained as follows: This invention performs impedance matching between a carbon-based antenna and a metal inductor loop, enabling the metal loop to form inductive coupling between the chip and the carbon-based antenna. This reduces signal attenuation between the antenna and the chip, resulting in an RFID tag with a coupled antenna structure that has a longer reading distance.

[0042] The following are three experimental results: Experiment 1: Using the same graphene antenna and metal circuit, and corrugated paper as the thickness test object, the reading distance of the RFID tag with the coupled antenna structure was tested by changing the thickness of the corrugated paper interlayer. Figure 2(a) shows the curve of the RFID tag reading distance of the coupled antenna structure as the frequency changes. Figure 2(b) shows the curve of the RFID tag reading distance of the coupled antenna structure as the corrugated paper interlayer thickness changes (thickness intervals of 0mm, 2mm, 5mm, and 10mm) at the national standard frequency of 920Hz.

[0043] Experiment 2: Using the same graphene antenna and metal circuit, and 3M foam as the thickness test object, the reading distance of the RFID tag with the coupled antenna structure was tested by changing the thickness of the 3M foam interlayer. Figure 3(a) shows the curve of the RFID tag reading distance of the coupled antenna structure as the frequency changes. Figure 3(b) shows the curve of the RFID tag reading distance of the coupled antenna structure as the thickness of the 3M foam interlayer changes (thicknesses of 0mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm) at the national standard frequency of 920Hz.

[0044] Experiment 3: Using the same graphene antenna and metal circuit, and rubber as the thickness test object, the reading distance of the RFID tag with the coupled antenna structure was tested by changing the thickness of the interlayer rubber. Figure 4(a) shows the curve of the RFID tag reading distance of the coupled antenna structure as the frequency changes. Figure 4(b) shows the curve of the RFID tag reading distance of the coupled antenna structure as the thickness of the 3M foam interlayer changes (thicknesses of 0mm, 3mm, 6mm, 9mm, 12mm, and 15mm) at the national standard frequency of 920Hz.

[0045] The test results of the above three experiments all confirm that by using an RFID tag with a coupled antenna structure and then using an RFID reader to transmit ultra-high frequency electromagnetic waves to read the information of the RFID tag with the coupled antenna structure, the maximum reading distance of the RFID tag with the coupled antenna structure will decrease as the distance between the ultra-high frequency antenna and the metal circuit increases. Therefore, the distance between the ultra-high frequency antenna and the metal circuit can be determined based on the maximum reading distance of the RFID tag with the coupled antenna structure, which is the thickness of the thickness test object in this invention. Thus, the RFID tag with the coupled antenna structure in this invention can act as a thickness sensor.

[0046] Example 2: The thickness testing method for RFID tags utilizing a coupled antenna structure provided by this invention is applied to humidity monitoring. It employs the thickness testing method for RFID tags using a coupled antenna structure as described in Example 1. The thickness testing object is a humidity-responsive shape memory polymer, such as... Figure 5 As shown in the example; in Example 1, step 7) is added after step 6). Step 7) includes determining the humidity of the corresponding environment based on the relationship between the thickness of the humidity-responsive shape memory polymer and the change of ambient humidity after determining the thickness of the humidity-responsive shape memory polymer.

[0047] The thickness of the humidity-responsive shape memory polymer changes with humidity. This change in thickness alters the response distance of the RFID tag with the coupled antenna structure to the ultra-high frequency electromagnetic waves emitted by the RFID reader, thus changing the maximum reading distance of the RFID tag. This is confirmed by the test results of the three experiments in Example 1. In this invention, the RFID tag with the coupled antenna structure can function as both a data recording module and a humidity sensor.

[0048] Example 3: The thickness testing method for RFID tags using a coupled antenna structure provided by this invention is applied to vaccine transport boxes. The method described in Example 1 uses the same thickness testing method for RFID tags with a coupled antenna structure. The thickness test object is the box material of the vaccine transport box, which is composed of a humidity-responsive shape memory polymer and an inner and outer layer of insulation material. The graphene antenna is disposed on the humidity-responsive shape memory polymer on the inner side of the vaccine transport box, and the metal circuit is disposed on the insulation material on the outer side of the vaccine transport box. Figure 6 As shown in the image.

[0049] Vaccine applications are unique, with harsh temperature and humidity conditions. Carbon-based materials have stable antenna performance, and when placed inside the vaccine transport box, they have virtually no impact on the vaccine. In particular, graphene has more stable performance compared to metals and other known materials such as carbon-based materials.

[0050] The vaccine transport box is also equipped with a data processing and analysis module and an alarm module. An RFID tag with a graphene coupled antenna structure, consisting of a metal circuit and a graphene antenna, together with the RFID reader, forms a humidity monitoring module. The RFID reader obtains the maximum reading distance data of the RFID tag by reading it and transmits this data to the data processing and analysis module. The data processing and analysis module determines the thickness of the humidity-responsive shape memory polymer based on the maximum reading distance, and then determines the humidity inside the vaccine transport box based on the relationship between the thickness of the humidity-responsive shape memory polymer and environmental humidity. The data processing and analysis module has a humidity threshold. When the humidity inside the vaccine transport box exceeds the humidity threshold, the data processing and analysis module triggers the alarm module to issue an alarm. Figure 7 As shown in the image.

[0051] Similar to Example 2, the thickness of the humidity-responsive shape memory polymer changes with humidity. As the humidity inside the vaccine transport box changes, the humidity-responsive shape memory polymer deforms, i.e., its thickness changes. The reading distance of the RFID tag with the graphene-coupled antenna structure changes accordingly. The RFID reader can determine whether the humidity inside the vaccine transport box is abnormal by observing the change in the reading distance of the RFID tag with the graphene-coupled antenna structure. Thus, this invention can serve as a humidity monitoring module for vaccine transport boxes. The RFID tag can be used to write vaccine information, acting as a data management module, and can also provide timely feedback on extreme humidity levels inside the vaccine transport box, ultimately triggering an alarm module, enabling real-time monitoring of the humidity inside the vaccine transport box.

[0052] To obtain the maximum reading distance of RFID tags with coupled antenna structures, changing the distance between the RFID reader and the thickness test object is usually achieved by moving the RFID tag, i.e., the thickness test object. However, in vaccine application scenarios, frequently moving the vaccine transport box is obviously inappropriate. In this embodiment, the RFID reader is an RFID performance tester, which is used to obtain the maximum reading distance of RFID tags with coupled antenna structures without changing the distance between the reader and the vaccine transport box. In this way, it is not necessary to move the vaccine transport box; simply bringing the RFID performance tester close to the RFID tag with coupled antenna structure (i.e., the vaccine transport box) is sufficient. The RFID performance tester is based on international standards (such as ISO / IEC 18046-3, EPCglobal Class 1 Generation 2, etc.) and can evaluate the maximum identification distance of RFID tags with coupled antenna structures by measuring parameters such as field strength and power.

[0053] Example 4: The difference between this embodiment and Embodiment 3 is that the RFID reader / writer has a minimum reading distance threshold. The RFID reader / writer is positioned at a distance of the minimum reading distance threshold from the vaccine transport box to read information from the RFID tags with coupled antenna structures. When the RFID reader / writer cannot read information from the RFID tags with coupled antenna structures, it triggers the alarm module to issue an alarm. Figure 8 As shown in the diagram, the minimum reading distance threshold is set based on the thickness of the humidity-responsive shape memory polymer, specifically the maximum reading distance of the RFID tag with the coupled antenna structure corresponding to the thickness of the humidity-responsive shape memory polymer when the extreme humidity threshold is reached inside the vaccine transport box.

[0054] Thus, when testing the maximum reading distance of the RFID tag with the coupled antenna structure, it is not necessary to move the vaccine transport box. The RFID reader can simply be positioned at a distance from the vaccine transport box at the minimum reading distance threshold to read the tag information. If the RFID reader can read the information of the RFID tag with the coupled antenna structure, it indicates that the thickness of the humidity-responsive shape memory polymer is within the normal range, and the humidity inside the vaccine transport box is acceptable. If the RFID reader cannot read the information of the RFID tag with the coupled antenna structure, it indicates that the thickness of the humidity-responsive shape memory polymer is too large, meaning the humidity inside the vaccine transport box is too high, and the alarm module can respond promptly. The alarm module is directly triggered by the RFID reader, ensuring a timely response and preventing the humidity monitoring module from malfunctioning when the data processing and analysis module fails.

[0055] The above are merely specific embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications or equivalent substitutions made to the present invention without departing from the spirit and scope thereof should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for testing the thickness of RFID tags using a coupled antenna structure, characterized in that, Includes the following steps: 1) An ultra-high frequency antenna and a metal circuit are respectively set on both sides of the thickness test object. The ultra-high frequency antenna and the metal circuit are opposite each other with the thickness test object in between. The metal circuit includes a metal ring and a chip. The ultra-high frequency antenna and the metal circuit form an RFID tag with a coupled antenna structure. 2) Use an RFID reader to transmit ultra-high frequency electromagnetic waves to read the information of the RFID tag in the coupled antenna structure; 3) Gradually change the distance between the RFID reader and the thickness test object to obtain the maximum reading distance. During the process of changing the distance, keep the frequency of the RFID reader transmission the same. 4) Gradually change the thickness of the test object with the same material, and set up the same specification UHF antenna and metal circuit on both sides respectively. Then repeat steps 2) and 3) to obtain the maximum reading distance corresponding to different thicknesses; 5) After repeated testing in step 4), obtain a list or linear relationship curve showing the correspondence between the thickness of the test object and the maximum reading distance of the RFID tag with the coupled antenna structure; 6) Set up UHF antennas and metal circuits of the same specifications on both sides of any thickness test object of the same material, and repeat steps 2) and 3) to obtain the maximum reading distance. Obtain the thickness of the thickness test object corresponding to the current maximum reading distance from the list or linear relationship curve in step 5).

2. The thickness testing method for RFID tags using a coupled antenna structure according to claim 1, characterized in that, The ultra-high frequency antenna includes a substrate and an antenna. The antenna is disposed on one side of the substrate, the substrate is attached to one side of the thickness test object, and the antenna is located between the substrate and the thickness test object, or the substrate is located between the antenna and the thickness test object.

3. The thickness testing method for RFID tags using a coupled antenna structure according to claim 2, characterized in that, The UHF antenna has a protective film on its outer side, which is attached to the UHF antenna. The antenna is located between the protective film and the thickness test object, or between the protective film and the substrate.

4. The thickness testing method for RFID tags using a coupled antenna structure according to claim 1, characterized in that, After step 3), add step 3-1). Step 3-1) includes adjusting the relative position between the UHF antenna and the metal circuit, and then repeating steps 2) and 3) to obtain the maximum reading distance. When the RFID tag with the coupled antenna structure obtains the maximum reading distance, the relative position between the UHF antenna and the metal circuit is the optimal coupling position. In step 4), on test objects of different thicknesses, the relative position between the UHF antenna and the metal circuit is also set to the optimal coupling position in step 3-1).

5. The thickness testing method for RFID tags utilizing a coupled antenna structure according to claim 1 or 4, characterized in that, After step 3), steps 3-2) and 3-3) are added. Step 3-2) involves gradually changing the frequency of the ultra-high frequency electromagnetic waves emitted by the RFID reader, and then repeating steps 2) and 3) to obtain the maximum reading distance corresponding to different frequencies. Step 3-3) involves obtaining a list or linear relationship curve between the frequency of the ultra-high frequency electromagnetic waves emitted by the RFID reader and the maximum reading distance of the RFID tag with the coupled antenna structure under the same thickness conditions. In step 4), after each change in the thickness of the test object with the same material, steps 3-2) and 3-3 are repeated.

6. An application of a thickness testing method for RFID tags utilizing a coupled antenna structure in humidity monitoring, characterized in that... The thickness testing method for RFID tags using a coupled antenna structure as described in any one of claims 1 to 5 is adopted, wherein the thickness testing object is a humidity-responsive shape memory polymer; after step 6), step 7) is added, which includes determining the humidity of the corresponding environment based on the relationship between the thickness of the humidity-responsive shape memory polymer and the change of ambient humidity after determining the thickness of the humidity-responsive shape memory polymer.

7. An application of a thickness testing method for RFID tags utilizing a coupled antenna structure in vaccine transport boxes, characterized in that... The thickness testing method for RFID tags using a coupled antenna structure, as described in any one of claims 1 to 5, is employed. The thickness testing object is the body material of the vaccine transport box, which is composed of a humidity-responsive shape memory polymer and an inner / outer layer of insulation material. The ultra-high frequency antenna is disposed on the humidity-responsive shape memory polymer on the inner side of the vaccine transport box, and the metal circuit is disposed on the insulation material on the outer side of the vaccine transport box. The vaccine transport box is also equipped with a data processing and analysis module and an alarm module. The RFID reader and the RFID tag with the coupled antenna structure together form a humidity monitoring module. The RFID reader obtains the maximum reading distance data of the RFID tag by reading it and transmits the maximum reading distance data to the data processing and analysis module. The data processing and analysis module is used to obtain the thickness of the humidity-responsive shape memory polymer based on the maximum reading distance, thereby determining the humidity inside the vaccine transport box. The data processing and analysis module is equipped with a humidity threshold and is also used to trigger the alarm module to issue an alarm when the humidity inside the vaccine transport box exceeds the humidity threshold.

8. The application of the thickness testing method for RFID tags using a coupled antenna structure according to claim 7 on vaccine transport boxes, characterized in that, The RFID reader / writer uses an RFID performance tester, which is used to obtain the maximum reading distance of RFID tags with coupled antenna structures without changing the distance between the reader and the vaccine transport box.

9. The application of the thickness testing method for RFID tags using a coupled antenna structure according to claim 7 on vaccine transport boxes, characterized in that, The RFID reader is equipped with a minimum reading distance threshold. The RFID reader is positioned at a distance of the minimum reading distance threshold from the vaccine transport box to read information from the RFID tag with the coupled antenna structure. When the RFID reader cannot read the information from the RFID tag with the coupled antenna structure, it will trigger the alarm module to issue an alarm.

10. The application of the thickness testing method for RFID tags using a coupled antenna structure according to claim 7 on vaccine transport boxes, characterized in that, The ultra-high frequency antenna is a carbon-based antenna.

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