CN111079251B - Radio frequency identification passive strain sensor of 3bit label - Google Patents
Radio frequency identification passive strain sensor of 3bit label Download PDFInfo
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- CN111079251B CN111079251B CN201911094228.0A CN201911094228A CN111079251B CN 111079251 B CN111079251 B CN 111079251B CN 201911094228 A CN201911094228 A CN 201911094228A CN 111079251 B CN111079251 B CN 111079251B
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- 230000005855 radiation Effects 0.000 claims abstract description 25
- 238000005452 bending Methods 0.000 claims abstract description 24
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- 229910052751 metal Inorganic materials 0.000 claims abstract description 11
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- 230000008859 change Effects 0.000 claims abstract description 7
- 238000005259 measurement Methods 0.000 claims abstract description 4
- 238000012544 monitoring process Methods 0.000 claims description 8
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 6
- 239000011889 copper foil Substances 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 239000004020 conductor Substances 0.000 claims description 3
- 238000012360 testing method Methods 0.000 claims description 3
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- 238000005516 engineering process Methods 0.000 description 15
- 229910052782 aluminium Inorganic materials 0.000 description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 10
- 230000036541 health Effects 0.000 description 5
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- 230000008569 process Effects 0.000 description 4
- 238000004088 simulation Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000003822 epoxy resin Substances 0.000 description 2
- 229920000647 polyepoxide Polymers 0.000 description 2
- 238000009864 tensile test Methods 0.000 description 2
- 238000012795 verification Methods 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
- G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
- G06K7/10009—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
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Abstract
The radio frequency identification passive strain sensor of the 3bit label is characterized by comprising a metal upper radiation surface, wherein the metal upper radiation surface consists of three bending symmetrical oscillator resonance structures (21, 22, 23) and a central circular microstrip patch (1); the integral radiation surface is used for transmitting and receiving information and communicating with a reader; three curved dipole resonant structures (21, 22, 23) are responsible for encoding information; the resonance frequency change of the circular microstrip patch (1) reflects the strain degree of the measured object; the sensor further comprises a dielectric substrate (3) located below the upper radiation surface of the metal. The strain measurement without an external power supply and a non-contact type chip is realized, the limitation of the external power supply and the wired contact is avoided, the manufacturing cost is greatly reduced, and the defects of larger use limitation and higher manufacturing cost of the active wired chip of the traditional strain sensor are overcome. The design that the coded resonator is grounded and the antenna for measuring the strain is not grounded is used for measuring the strain degree of the solid surface subjected to stress and strain, and has certain anti-interference capability.
Description
Technical Field
The invention belongs to the technical field of structural health monitoring and microstrip antennas, and designs an anti-interference passive wireless chipless miniaturized RFID strain sensor based on the microstrip antennas.
Background
In the long-term use process of the structural body, structural damage to a certain degree can necessarily occur, and the safety use of the structural body can be influenced to a certain degree by accumulation. Structural damage refers to changes in structural material parameters and their geometric characteristics. Such damage tends to accumulate slowly and is not easily detected, and once the limits that the structure can withstand are broken through, it can lead to significant safety hazards. For a long time, attempts have been made to monitor the relevant characteristics of the target using various approaches to assess whether the target can continue to function. Structural health monitoring (Structural Health Monitoring, SHM) began to evolve over the last decade and became an emerging topic across disciplines. The structural health monitoring technology is as follows: and detecting response by using a certain device on the site of the monitored object by using a nondestructive sensing technology, and combining the characteristic analysis of the structural system to evaluate the damage or degradation degree of the target structure and position the specific position of the damage.
Radio frequency identification (Radio Frequency Identification, RFID) technology is a new type of automatic identification technology that has been developed rapidly in recent years. It uses RF front end to emit radio frequency signal to activate antenna, then receives reflected signal, reads data and identifies target. RFID technology has a great advantage in that its identification process requires no manual intervention, and is widely applicable in harsh environments. The technology is deeply in the aspects of life at present, is tightly combined with technologies such as the Internet of things and automation, and can realize large-scale information exchange. RFID systems are generally classified into two main categories, active and passive, and passive backscatter RFID systems combined with microstrip antennas are more widely used in real life. Because the wireless tag works in the ultra-high frequency band, the data of the tag is transmitted to the reader by utilizing the electromagnetic wave reflection of the target, so that the wireless transmission is realized. The system has the advantages of high integration, low cost, high communication speed, strong anti-interference capability and the like.
The chipless RFID technology is a novel RFID technology at present, the characteristics of non-contact reading, flexibility and the like of the traditional RFID are maintained, and meanwhile, the production cost is greatly reduced because no built-in chip is arranged. Chipless RFID tags refer to radio frequency identification tags that do not contain silicon chips, and are typically based on conventional printed circuit technology that can be printed directly onto an object substrate to widen the application. The appearance and development of the chipless RFID technology continuously fills some limitations and shortages of the traditional RFID technology, and promotes the progress of the technology of the Internet of things.
Disclosure of Invention
Object of the invention
Based on the application requirement, the invention discloses a radio frequency identification passive strain sensor of a 3bit tag, which utilizes the approximately linear relation between the electrical performance parameter of an antenna and the size of the antenna, and when the RFID patch antenna is stressed to generate strain to cause the size change, the resonant frequency of the antenna also changes. It is thus possible to consider measuring the change in strain by monitoring the change in resonant frequency of the RFID antenna. The RFID patch antenna of the present invention may be used as a strain sensor.
The technical proposal of the invention
A design principle method of a radio frequency identification passive strain sensor of a 3-bit tag is characterized by comprising the following steps: the invention realizes the integrated non-contact detection of the three functions of signal receiving, information coding and signal sending of the sensor.
Structural design, its characterized in that: the sensor comprises a metal upper radiation surface, a metal lower radiation surface and a metal upper radiation surface, wherein the metal upper radiation surface consists of three bending symmetrical oscillator resonant structures (21, 22 and 23) and a central circular microstrip patch (1); the integral radiation surface is used for transmitting and receiving information and communicating with a reader; three curved dipole resonant structures (21, 22, 23) are responsible for encoding information; the resonance frequency change of the circular microstrip patch (1) reflects the strain degree of the measured object. The sensor further comprises a dielectric substrate (3) located below the upper radiation surface of the metal.
The bottom of the sensor is attached to the surface of the solid structure to be tested through glue.
The bending dipoles of the upper radiation surface are adjacently placed in sequence, so that the influence of mutual coupling is reduced: the radian of the resonator (21) is 64 degrees, the radian of the resonator (22) is 70 degrees, and the radian of the resonator (23) is 74 degrees. Rectangular structures are arranged at two ends of the three resonators, the rectangular long range lt is 2.8-3.3 mm, and the rectangular wide range wt is 2.3-2.8 mm. The radius of the circular microstrip patch at the center is in the range of 13.8 mm-14.4 mm.
The dielectric substrate (3) is made of high-frequency plate material, and the circular microstrip patch (1) and the three bending symmetrical oscillator resonant structures (21, 22 and 23) in the upper radiating surface are copper foil sheets.
According to an optimized technical scheme, the sensor is provided with a lower radiation surface (4). Because the lower radiation surface (4) corresponding to the bending symmetrical oscillator resonator is wrapped with the copper foil, when the sensor is attached to the surface of the solid structure, the bending symmetrical oscillator is not in direct contact with the solid structure, even if a measurement structure object is a conductor, when the structure is deformed until cracks are generated, the resonance frequency of the bending symmetrical oscillator resonator is still stable all the time, and the technical measure ensures that the 3-bit encoder formed by the bending symmetrical oscillator resonator can stably store information, which is the second innovation of the invention.
The lower radiation surface (4) is a copper foil, the length range is 33 mm-38 mm, the width range is 33 mm-38 mm, and the thickness is 1.6mm.
Further optimizing technical measures, the round radius of the center of the lower radiating surface (4) is larger than that of the round microstrip patch (1) at the center of the upper radiating patch, so that when the tag is attached to the surface of a measured solid structure, the round microstrip patch at the center of the upper radiating patch is grounded through a dielectric substrate, and the lower radiating surface (4) is arranged below the three bending dipole resonance structures (21, 22 and 23) and is not in contact with the measured solid structure. In this way, when the measured object is a conductor, in case of cracks in the strain process, the three bending dipoles for encoding resonance structures cannot be interfered by the cracks, the resonance frequency of the dipoles remains unchanged, and the strain degree of the solid structure is analyzed only through the change of the electrical characteristics of the resonance frequency of the circular microstrip patch.
The radius of the circle hollowed out in the middle of the lower radiation surface (4) is 17.8-18.3 mm, so that the circle is ensured to be larger than the range of the circular microstrip patch (1) and not more than the range of three bending symmetrical oscillator resonators (21, 22, 23).
The three bending dipole resonators (21, 22, 23) have a coding function, so that each sensor has a unique code, and by utilizing the characteristic, a plurality of tag sensors can be read simultaneously by using the reader peripheral equipment, so that local stress monitoring in a large range is realized.
The invention adopts the wireless radio frequency identification ((Radio Frequency Identification, RFID) technology to realize the non-contact chip-free strain measurement without an external power supply, avoids the limitation of wired contact between an external power supply and a wired power supply, greatly reduces the manufacturing cost, and overcomes the defects of larger use limitation and higher manufacturing cost of the traditional strain sensor active wired chip.
Drawings
FIG. 1 is a schematic diagram of a sensor as a whole
FIG. 2 sensor top view
Fig. 3 sensor bottom view
FIG. 4 sensor physical diagram
FIG. 5 sensor strain resonant frequency offset fitting map
Numerical marking:
circular microstrip patch (1), three curved dipoles resonator (21, 22, 23), dielectric substrate (3), lower radiating surface (4)
Detailed Description
The technical scheme of the invention is further described below with reference to the accompanying drawings and the examples.
The invention creatively introduces a chipless RFID technology to design a passive wireless sensor based on back scattering, integrates the functions of receiving signals, coding information and transmitting signals, does not comprise additional integrated circuit modules or independent electronic components, saves the manufacturing cost and is smaller than a common coding label.
Example 1
As shown in FIG. 1, the passive wireless chipless RFID sensor of the embodiment is characterized in that the dielectric substrate (3) is made of FR4 epoxy resin board, and the relative dielectric constant epsilon r The upper radiation surface of the sensor comprises three bending symmetrical resonator resonators (21, 22, 23) and a central circular microstrip patch (1), and the lower radiation surface (4) is formed by printing copper foil sheets serving as materials on a dielectric substrate. The main parameter dimensions of the sensor are shown in table 1 below:
table 1 sensor principal parameter size table
| Main parameters | Wt | lt | a | b | w | h |
| Size of the device | 2.5mm | 3mm | 14mm | 18mm | 35mm | 1.6mm |
Wherein a is the diameter of the circular microstrip patch (1), and b is the diameter of the circle hollowed out by the center of the lower radiation surface (4).
The working principle of this embodiment is as follows:
the main resonance structure is formed by three bending dipole resonators (21, 22, 23) and a central circular microstrip patch (1). The three bending dipoles are half-wavelength resonators, and different radians of the bending dipoles correspond to different resonant frequencies, so that the 3-bit encoder carried by the tag is characterized to store information. When the radio frequency signal emitted by the reader antenna of the system contacts the sensor, the energy is provided for the sensor, and meanwhile, the bending symmetrical oscillator resonators passing through different radians can generate resonance at corresponding frequency points.
The lower radiation surface (4) of the tag is directly contacted with the surface of the object to be measured, namely the solid structure, when the solid structure is deformed, the resonance frequency of the circular microstrip patch (1) positioned above the solid structure is influenced by synchronous deformation, and the circular microstrip patch is deviated according to a certain rule. The circular microstrip patch (1) is deformed into an ellipse, and the relation between the long axis of the circular microstrip patch and the resonance frequency of the circular microstrip patch (1) has the following formula:
wherein the equivalent dielectric constant is ε ref C is the speed of light in vacuum, and the resonant frequency is f when the long axis length is L and the compensation length is DeltaL r 。
And the resonance frequency is shifted by f re (ε s ) And strain amount epsilon s Is approximated by:
f re (ε S )＝f re (1-ε s )
verification step
Verification of novel tamper resistant passive wireless chipless miniaturized RFID strain sensor using FR4 epoxy resin dielectric substrate (dielectric constant ε r =4.4, loss tangent tan δ= 0.1646) was made to the dimensions given, as in fig. 4.
To verify the strain sensor, a tensile test was performed on it in a microwave dark room. The design is that the strain of the tag antenna is converted by stretching an aluminum plate (a tested structure) and measuring the stress of the aluminum plate. The tension is directly read by a dynamometer on the stretcher, and the strain generated by the stress of the antenna is calculated by the following formula:
wherein F is the tensile force applied by the stretcher, epsilon is the strain value of the tested object under the tensile force F, E is the elastic modulus of the aluminum plate test piece, A is the cross section area of the aluminum plate test piece, and 4mmx60mm. The stress magnitude of the measured object is calculated by detecting the resonance frequency deviation condition of the stress antenna attached to the aluminum plate. The specific experimental steps are as follows:
(1) Firstly, an aluminum plate for tensile test is prepared, the surface of the aluminum plate is polished, and the surface is rough as much as possible so as to facilitate the attachment of the RFID strain antenna.
(2) The patch antenna was tightly adhered to the middle of the aluminum plate using a strong adhesive.
(3) The aluminum plate is fixed on a stretcher and adjusted to a proper position, and a reader is fixed.
(4) And a reader is used for receiving and transmitting signals, and the record stores data.
(5) Starting a stretcher, gradually applying tension to the measured aluminum plate at an increasing step of 2kN from 0kN, recording an actual tension value after the reading of the to-be-measured electrometer is stable, and repeating the step (4) until the tension reaches 12kN.
Fig. 5 is a comparison of simulation results and experimental results of the sensor strain. As can be seen from fig. 5, the simulation result and the experimental result substantially conform to the theoretical derivation, i.e. the resonant frequency offset of the circular microstrip patch antenna is linearly related to the strain thereof. The difference between the simulation and the actual experiment is the error of the manufacturing process of the laboratory antenna, which leads to certain deviation of the resonance parameters of the circular microstrip patch antenna.
Can be applied in the following scenarios: structural health monitoring
The anti-interference passive wireless chipless miniaturized RFID strain sensor produced by the design is stuck on the surface of a solid structure which is easy to generate strain in a building. The strain degree of the solid structure can be monitored in the process of slowly deforming the solid structure, and the solid structure can be timely prevented and repaired before exceeding a critical value, so that large-scale safety accidents are avoided.
Claims (9)
1. The radio frequency identification passive strain sensor of the 3bit label is characterized by comprising a metal upper radiation surface, wherein the metal upper radiation surface consists of three bending symmetrical oscillator resonance structures (21, 22, 23) and a central circular microstrip patch (1); the integral radiation surface is used for transmitting and receiving information and communicating with a reader; three curved dipole resonant structures (21, 22, 23) are responsible for encoding information; the resonance frequency change of the circular microstrip patch (1) reflects the strain degree of the measured object; the sensor also comprises a dielectric substrate (3) positioned below the upper metal radiation surface; the bending dipoles of the upper radiation surface are adjacently arranged in sequence, the radian of the first resonator (21) is 64 degrees, the radian of the second resonator (22) is 70 degrees, and the radian of the third resonator (23) is 74 degrees; rectangular structures are arranged at two ends of the three resonators, the rectangular length range lt is 2.8-3.3 mm, and the rectangular wide range wt is 2.3-2.8 mm; the three bending dipoles are half-wavelength resonators, and different radians of the bending dipoles correspond to different resonant frequencies, so that the 3-bit encoder carried by the tag is characterized to store information.
2. The sensor of claim 1, wherein the sensor base is attached to the surface of the solid structure under test by glue.
3. The sensor of claim 1, wherein the radius of the circular microstrip patch ranges from 13.8mm to 14.4mm.
4. A sensor according to claim 1, characterized in that the dielectric substrate (3) is a high-frequency plate material, and the circular microstrip patch (1) in the upper radiating plane and the three curved dipole resonator structures (21, 22, 23) are copper foil.
5. A sensor according to claim 1, characterized in that the optimization solution sensor is provided with the following radiation surface (4): when the sensor is attached to the surface of a solid structure, the bending dipoles are not in direct contact with the solid structure, and even if the object of the measurement structure is a conductor, the resonance frequency of the bending dipoles remains stable all the time when the structure is deformed until cracks occur.
6. A sensor according to claim 5, characterized in that the lower radiating surface (4) is a copper foil with a length in the range of 33mm to 38mm and a width in the range of 33mm to 38mm and a thickness of 1.6mm.
7. A sensor according to claim 5 or 6, characterized in that the lower radiating surface (4) is hollowed out with a larger radius of circle than the circular microstrip patch (1) in the center of the upper radiating patch.
8. A sensor according to claim 7, characterized in that the radius of the circle hollowed out in the middle of the lower radiating surface (4) has a value of 17.8 mm-18.3 mm, ensuring that it is not more than the range of three curved dipole resonators (21, 22, 23) than the circular microstrip patch (1).
9. A sensor according to claim 1, characterized in that three bending dipole resonators (21, 22, 23) have a coding function, each sensor having a unique code, by means of which a plurality of tag sensors can be read simultaneously using a reader peripheral device, enabling a large range of local stress monitoring.
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| CN112097963B (en) * | 2020-08-27 | 2021-10-08 | 西安电子科技大学 | Stress sensor based on chipless radio frequency identification tag |
| CN112697336B (en) * | 2020-12-01 | 2021-09-14 | 同济大学 | Bolt looseness sensor and monitoring system based on overlapped fan annular patch antenna |
| CN113705746A (en) * | 2021-08-19 | 2021-11-26 | 惠州恒德远实业有限公司 | Passive flexible chipless RFID strain detection method and system |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009103042A2 (en) * | 2008-02-15 | 2009-08-20 | Board Of Regents, The University Of Texas System | Passive wireless antenna sensor for strain, temperature, crack and fatigue measurement |
| CN107946759A (en) * | 2017-11-15 | 2018-04-20 | 北京工业大学 | A kind of array strain transducer based on microstrip antenna formula RFID tag |
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| US8690068B2 (en) * | 2012-05-21 | 2014-04-08 | Warsaw Orthopedic, Inc. | Miniaturized UHF RFID tag for implantable medical device |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009103042A2 (en) * | 2008-02-15 | 2009-08-20 | Board Of Regents, The University Of Texas System | Passive wireless antenna sensor for strain, temperature, crack and fatigue measurement |
| CN107946759A (en) * | 2017-11-15 | 2018-04-20 | 北京工业大学 | A kind of array strain transducer based on microstrip antenna formula RFID tag |
Non-Patent Citations (1)
| Title |
|---|
| 基于RFID的微带天线应变传感器的仿真分析;宋国荣;文硕;吕炎;张斌鹏;窦致夏;吴斌;何存富;;北京工业大学学报(第05期);全文 * |
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