Strain sensor based on open resonant ring, rfid tag and rfid system
By using a passive strain sensor based on an open resonant ring and an RFID tag system, the problem of existing wireless strain sensors requiring battery power has been solved, enabling large-scale strain monitoring that is low-cost, easy to deploy and maintain.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- FUZHOU UNIV
- Filing Date
- 2025-05-20
- Publication Date
- 2026-06-23
AI Technical Summary
Existing wireless strain sensors rely on battery power, resulting in high costs and difficulties in deployment and maintenance.
Design a passive strain sensor and RFID tag system based on an open resonant ring. The system uses resonant frequency shift to sense strain and detects frequency changes via an RFID reader, eliminating the need for battery power.
It enables large-scale strain monitoring that is low-cost, easy to deploy and maintain, and is suitable for structural health monitoring of long structures.
Smart Images
Figure CN224398579U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of sensor technology, and in particular to strain sensors, RFID tags and RFID systems based on open resonant rings. Background Technology
[0002] Strain is a key indicator reflecting the stress state and deformation of engineering structures (such as bridges, tunnels, pipelines, and buildings). Real-time strain monitoring allows for precise identification of structural deformation trends under loads (such as wind loads, earthquakes, vehicle loads, and soil and water pressure) or environmental factors (temperature, humidity, etc.), enabling timely detection of potential safety hazards. Strain monitoring can track the degradation process of structural performance and predict remaining lifespan. Combined with the Internet of Things, edge computing, and big data analytics, strain monitoring provides intelligent decision-making support for structural health assessment and reinforcement. While traditional resistive strain sensors offer high accuracy and low cost, their deployment is difficult, making them unsuitable for long structures. Fiber optic sensors, while offering advantages in distributed strain monitoring, suffer from high deployment and maintenance costs.
[0003] In recent years, with the rise of wireless sensor networks in structural health monitoring, wireless strain sensors have been widely used. However, existing wireless strain sensors all rely on their own power source to complete strain sensing, resulting in high costs and frequent battery replacements. Therefore, a new type of sensor needs to be designed. Utility Model Content
[0004] This invention proposes a strain sensor, RFID tag, and RFID system based on an open resonant ring, which solves the problems of existing strain sensors requiring wired connection, batteries, and high cost.
[0005] The technical solution of this utility model is implemented as follows:
[0006] This invention first proposes a strain sensor based on an open resonant ring, including a substrate. A grid-shaped resonant ring is provided on the front surface of the substrate. Openings are provided on the four sides of the outer periphery of the resonant ring, and the four openings are arranged in a centrally symmetrical manner.
[0007] Preferably, the substrate is an epoxy resin board.
[0008] Preferably, the substrate has a thickness of 1.5 mm, a dielectric constant of 4.3, and a loss tangent of 0.02.
[0009] Preferably, the resonant ring is a copper resonant ring printed on the substrate.
[0010] Preferably, the thickness of the resonant ring is 0.035 mm and the conductivity is 5.96 × 10⁻⁶. 7 S / m.
[0011] Preferably, the width of each of the four sides of the resonant ring is 1 mm.
[0012] Preferably, the resonant ring includes an inner cross arm and an outer square frame, and the opening is located on the outer square frame on one side of the outer end of the inner cross arm, and the opening is a rectangular opening.
[0013] Preferably, the number of strain sensors based on the open resonant ring is three, and they are arranged at a 120° angle interval between each other.
[0014] The present invention further proposes an RFID tag, including the strain sensor based on the open resonant ring described above.
[0015] This invention reiterates the RFID system, which includes the RFID tag described above, and also includes an RFID reader.
[0016] The beneficial effects of this utility model are as follows: The strain sensor based on the open resonant ring of this utility model is a passive sensor. When subjected to external strain, the antenna resonance characteristics shift, thereby sensing the strain. The strain sensor based on the RFID tag antenna does not require a battery and has the advantages of low cost, simple deployment, easy maintenance, and large-scale deployment. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a schematic diagram of the structure of Example 1;
[0019] Figure 2 for Figure 1 The right view;
[0020] Figure 3 The resonant frequency shift RFS is linearly related to the strain ε;
[0021] Figure 4 This is a schematic diagram of the structure of Example 2;
[0022] Figure 5 This is a schematic diagram of the structure of Example 3.
[0023] In the diagram: 1-resonant ring, 2-substrate, 3-opening, 4-inner cross arm, 5-outer frame. Detailed Implementation
[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0025] Example 1
[0026] like Figure 1 and Figure 2 The strain sensor based on the open resonant ring includes a substrate. A grid-shaped resonant ring is provided on the front surface of the substrate. Openings are provided on the four sides of the outer periphery of the resonant ring, and the four openings are arranged in a centrally symmetrical manner.
[0027] Preferably, the substrate is an epoxy resin board with a thickness of 1.5 mm, a dielectric constant of 4.3, and a loss tangent of 0.02.
[0028] Preferably, the resonant ring is a copper resonant ring printed on the substrate, the resonant ring having a thickness of 0.035 mm and an electrical conductivity of 5.96 × 10⁻⁶ mm. 7 S / m, the width of each of the four sides of the resonant ring is 1mm.
[0029] Preferably, the resonant ring includes an inner cross arm and an outer square frame, and the opening is located on the outer square frame on one side of the outer end of the inner cross arm, and the opening is a rectangular opening.
[0030] The open-loop resonant ring has an initial resonant frequency f0. After being subjected to strain ε, its geometry changes, resulting in a resonant frequency shift RFS (Δf = f). ε -f0). For example Figure 3 As shown, simulation using Comsol software demonstrates a linear relationship between the resonant frequency shift RFS and the strain ε. Furthermore, the sensitivity of strain detection is K = RFS / ε.
[0031] The strain detection sensitivity includes both the length and width directions of the open-ended resonant ring. When the open-ended resonant ring receives strain parallel to the length direction, the sensitivity is K. L When subjected to strain parallel to the width direction, the sensitivity is K. w .against Figure 1 The strain detection sensitivity obtained from the simulation is K. L =K w = -3.975kHz / με. The negative sign indicates that strain reduces the resonant frequency.
[0032] Example 2
[0033] like Figure 4 The difference between this embodiment and embodiment 1 is that the number of strain sensors based on the open resonant ring is three, and they are arranged at a 120° angle interval.
[0034] A single strain sensor based on an open-loop resonant ring can only detect uniaxial strain. To achieve quantitative detection of both strain magnitude and direction, a [further design is needed]. Figure 4 The sensor array is shown. Assuming the strain direction θ of the measured structure is the angle between the strain and the positive y-axis of the sensor 1's independent coordinate system, based on trigonometric relationships and vector decomposition principles, the relationship between the RFS of the sensor unit and the strain can be expressed as:
[0035] K L ε|cos(θ-θ n )|+K W ε|sin(θ-θ n )|=Δf n (1)
[0036] In the formula, ε is the magnitude of strain, and θ n (n = 1, 2, 3) represents the angular interval of the nth sensor unit, θ n The RFS generated for the nth sensor unit.
[0037] Based on equation (1), the frequency shift equations of the three sensor units constitute a set of equations:
[0038]
[0039] In the formula, the magnitude ε and direction θ of the strain can be solved using the least squares method:
[0040]
[0041] Example 3
[0042] RFID tags, including strain sensors based on open resonant rings as described in Example 1 or Example 2.
[0043] Example 4
[0044] The RFID system includes the RFID tag described in Example 3, and also includes an RFID reader.
[0045] like Figure 5 As shown, the RFID reader transmits an electromagnetic wave signal containing the resonant frequency of the tag antenna to the tag antenna array and receives the reflected signal from the tag antenna. By detecting the power frequency of the reflected signal from the tag antenna, the frequency corresponding to the minimum reflected power is the resonant frequency f of the strain sensor. ε This allows us to obtain the change in the resonant frequency Δf of the strain sensor relative to its initial state.n .
[0046] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. Open resonant ring based strain sensor, characterized in that: The substrate is provided with a cross-shaped resonant ring on the front surface, four edges of the resonant ring are provided with openings, and the four openings are arranged in a central symmetry. The resonant ring comprises inner cross arms and an outer square frame, the openings are located on the outer square frame on one side of the outer end of the inner cross arms, and the openings are rectangular openings.
2. The open resonant ring based strain sensor of claim 1, wherein: The substrate is an epoxy resin plate.
3. The open resonant ring based strain sensor of claim 2, wherein: The thickness of the substrate is 1.5 mm, the dielectric constant is 4.3, and the loss tangent is 0.
02.
4. The open resonant ring based strain sensor of claim 1, wherein: The resonant ring is a copper resonant ring printed on the substrate.
5. The open resonant ring based strain sensor of claim 4, wherein: The resonant ring has a thickness of 0.035 mm and an electrical conductivity of 5.96 x 10 7 S / m.
6. The open resonant ring based strain sensor of claim 4, wherein: The width of the four edges of the resonant ring is 1 mm.
7. The open resonant ring based strain sensor according to any one of claims 1-6, wherein: The number of the strain sensors based on the opening resonant ring is three, and the three strain sensors are arranged at an interval of 120°.
8. An RFID tag characterized by: The strain sensor based on the opening resonant ring comprises the substrate, the cross-shaped resonant ring provided on the front surface of the substrate, four edges of the resonant ring are provided with openings, and the four openings are arranged in a central symmetry.
9. An RFID system characterized by: The RFID tag comprises the strain sensor based on the opening resonant ring, and further comprises an RFID reader.