Wireless passive strain sensor, RFID tag and RFID system

Abstract

The utility model provides a wireless passive strain sensor, an RFID tag and an RFID system. A wireless passive strain sensor comprises a substrate, the front surface of the substrate is provided with an outer resonant ring, the outer resonant ring is internally provided with a concentric inner resonant ring, and the outer resonant ring and the inner resonant ring are respectively provided with a first opening and a second opening which are opposite to each other. The wireless passive strain sensor does not need a power supply or wiring, and is easy to maintain, low in cost and long in service life.

Description

TECHNICAL FIELD

[0001] The utility model relates to sensor technical field especially relates to a wireless passive strain sensor, RFID label and RFID system. BACKGROUND

[0002] Various building structures such as bridge, pipeline, tower etc. are prone to tensile strain or bending strain under the action of external environment or self-aging, which leads to performance degradation and thus causes safety hazards, so it is necessary to monitor the strain generated by the structure in real time in many engineering projects, and then to evaluate the health condition of the structure. In view of the safety accidents caused by the aging of building structures over time, reducing or avoiding the economic loss and adverse social influence caused by the health problems of the structure, installing appropriate structure health monitoring system on these structures will bring extremely important economic and social benefits.

[0003] Strain sensor is an important component of structure health monitoring system. Fiber grating, resistance type and other strain sensors all need uninterrupted power supply to complete strain monitoring and need data line to return monitoring data to the system, and the dependence on power supply leads to high cost of these sensors. At the same time, the traditional wired active strain sensor is complex to lay and needs frequent maintenance. SUMMARY

[0004] The utility model provides a wireless passive strain sensor, RFID label and RFID system, solve the problem that the existing wired active strain sensor is complex to lay, high in cost and needs frequent maintenance.

[0005] The technical scheme of the utility model is realized as follows:

[0006] The utility model discloses a wireless passive strain sensor first, including the substrate, the front surface of substrate is provided with the outer resonance ring, the concentric inner resonance ring is arranged in the outer resonance ring, and the first opening and the second opening opposite are respectively set up on the outer resonance ring and the inner resonance ring.

[0007] Preferably, the substrate is an epoxy resin plate.

[0008] Preferably, the dielectric constant of the substrate is 4.4, and the thickness t is 1.6 mm.

[0009] Preferably, the outer resonance ring and the inner resonance ring are both copper rings.

[0010] Preferably, the thickness of the outer resonance ring and the inner resonance ring is 35.0 microns.

[0011] Preferably, the average radius r0 of the outer resonance ring and the inner resonance ring is 5.0 mm, the spacing d between the outer resonance ring and the inner resonance ring is 0.5 mm, and the ring width c is 0.5 mm.

[0012] Preferably, the electrical conductivity of the outer resonant ring and the inner resonant ring is 5.8*10 7 S / m.

[0013] Preferably, the width of the first opening and the second opening is g=1.0mm.

[0014] The utility model further provides an RFID tag, including the wireless passive strain sensor above.

[0015] The utility model further provides an RFID system, including the RFID tag above, still include RFID reader.

[0016] The utility model discloses the wireless passive strain sensor of the utility model, need not power supply, also need not wiring, easy maintenance, low in cost, long in service life. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical scheme in the embodiment of the utility model or prior art, below will to the drawing used in the embodiment or prior art description of the simple introduction, obviously, the drawing in the following description only some embodiments of the utility model, for those skilled in the art, under the premise of not paying creative labor, still can obtain other drawings according to these drawings.

[0018] Figure 1 It is the structural schematic diagram of example 1;

[0019] Figure 2 It is the structural schematic diagram of example 3;

[0020] Figure 3 It is the simulation result drawing of microstrain and frequency relationship;

[0021] Figure 4 It is the simulation result drawing of resonant frequency and microstrain relationship.

[0022] In the drawing: 1-outer resonant ring, 2-inner resonant ring, 3-substrate, 4-wireless passive strain sensor, 5-structure to be measured, 6-RFID transmitter, 7-RFID receiver, 8-second opening. DETAILED DESCRIPTION

[0023] The technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model, and obviously, the described embodiments are only part of the embodiments of the utility model, not all embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the utility model.

[0024] Example 1

[0025] Reference Figure 1 A wireless passive strain sensor 4 includes a substrate 3. An outer resonant ring 1 is disposed on the front surface of the substrate 3. A concentric inner resonant ring 2 is disposed inside the outer resonant ring 1. The outer resonant ring 1 and the inner resonant ring 2 are respectively provided with opposite first openings and second openings 8.

[0026] Preferably, the substrate 3 is an epoxy resin board with a dielectric constant of 4.4 and a thickness of t = 1.6 mm.

[0027] Preferably, both the outer resonant ring 1 and the inner resonant ring 2 are copper rings, both have a thickness of 35.0 μm, an average radius r0 = 5.0 mm, a spacing d = 0.5 mm between them, a ring width c = 0.5 mm, and an electrical conductivity of 5.8 × 10⁻⁶. 7 S / m.

[0028] Preferably, the width of both the first opening and the second opening 8 is g = 1.0 mm.

[0029] A method for fabricating a wireless passive strain sensor includes the following steps: (1) drawing the designed structure using CAD drawing software; (2) printing the pattern onto transfer paper using a laser printer, and transferring the pattern on the transfer paper to the copper-clad FR-4 side using a laminator; (3) treating the FR-4 copper-clad board using a chemical etching method, etching the uncoated copper surface using anhydrous ferric chloride (FeCl3, AR, 99%), and washing away excess solution using a brush dipped in lead-free environmentally friendly board cleaning water; (4) cutting the entire board into individual sensor units using a diamond wire cutter.

[0030] Example 2

[0031] RFID tag, including a wireless passive strain sensor 4 as described in Example 1.

[0032] Example 3

[0033] Reference Figures 2-4 The RFID system includes the RFID tag described in Example 2, and also includes an RFID reader. The RFID reader includes an RFID transmitter 6 and an RFID receiver 7.

[0034] The detection mechanism of a wireless passive strain sensor, such as Figure 2As shown, when the measured structure 5 experiences strain, the wireless passive strain sensor 4, tightly bonded to its surface, deforms accordingly, causing a change in the average radius r0 of the outer and inner resonant rings. This modulates the equivalent inductance and capacitance of the outer and inner resonant rings, resulting in a shift in their resonant frequency f. Through the differential design of the opposite openings of the outer and inner resonant rings, tensile or compressive strain will increase or decrease the mutual inductance effect between the two rings, causing the equivalent capacitance and inductance to change in opposite directions, significantly amplifying the sensitivity of the frequency shift. The microwave signal emitted by the RFID transmitter 6 excites the resonant ring to generate an electromagnetic response. The frequency of the resonant valley in the spectrum characteristics of its reflected signal is linearly related to the strain. The RFID receiver 7 can calculate the strain value by detecting the frequency shift and substituting it into the calibration equation. The entire process requires no external power supply or physical wiring, achieving self-sufficiency in energy and wireless data transmission through electromagnetic coupling, ultimately completing high-precision, interference-resistant strain detection.

[0035] To verify the effectiveness of this invention, in COMSOL An electromagnetic simulation platform was used to construct a three-dimensional full-wave model of a wireless passive strain sensor, with the substrate dielectric constant set to 4.4 and the conductivity of the outer and inner resonant rings to 5.8 × 10⁻⁶. 7 S / m, such as Figure 3 As shown, strain is generated by simulating the structure by changing the radii of the outer and inner resonant rings, and a uniform strain field of 0-4000με is applied for parametric scanning.

[0036] Figure 4 Simulation results show that the initial resonant frequency of the wireless passive strain sensor is 4.66 GHz. Under tensile strain, the resonant frequency shifts linearly with strain, and the sensitivity reaches 6.523 kHz / με(R). 2 =0.9794).

[0037] 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. A wireless passive strain sensor, characterized in that, The device includes a substrate, an outer resonant ring disposed on the front surface of the substrate, a concentric inner resonant ring disposed inside the outer resonant ring, and a first opening and a second opening respectively opened on the outer resonant ring and the inner resonant ring.

2. The wireless passive strain sensor as described in claim 1, characterized in that, The substrate is an epoxy resin board.

3. A wireless passive strain sensor as described in claim 2, characterized in that, The substrate has a dielectric constant of 4.4 and a thickness of t = 1.6 mm.

4. A wireless passive strain sensor as described in claim 1, characterized in that, Both the outer resonant ring and the inner resonant ring are made of copper.

5. A wireless passive strain sensor as described in claim 4, characterized in that, The thickness of both the outer resonant ring and the inner resonant ring is 35.0 μm.

6. A wireless passive strain sensor as described in claim 5, characterized in that, The average radius r0 of the outer resonant ring and the inner resonant ring is 5.0 mm, the distance d between the outer resonant ring and the inner resonant ring is 0.5 mm, and the ring width c is 0.5 mm.

7. A wireless passive strain sensor as described in claim 4, characterized in that, The conductivity of the outer resonant ring and the inner resonant ring is 5.8 × 10⁻⁶. 7 S / m.

8. A wireless passive strain sensor as described in claim 1, characterized in that, The width of both the first opening and the second opening is g = 1.0 mm.

9. An RFID tag, characterized in that: Including a wireless passive strain sensor as described in any one of claims 1-8.

10. An RFID system, characterized in that: It includes the RFID tag as claimed in claim 9, and also includes an RFID reader.

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