Real-time self-driven wireless sensor based on friction nanometer generator

Abstract

The invention discloses a real-time self-driven wireless sensor based on a friction nano-generator. The real-time self-driven wireless sensor comprises the friction nano-generator, a discharging device, a sliding capacitive displacement sensor, an inductance coil and a receiving circuit, the sliding capacitive displacement sensor and the inductance coil form a parallel LC resonance circuit, and the friction nano generator supplies power to the LC resonance circuit through the discharge device; the sliding capacitive displacement sensor comprises an upper conductive flat plate and a lower conductive flat plate which are oppositely arranged, and at least one dielectric material layer located between the upper conductive flat plate and the lower conductive flat plate; the upper conductive flat plate is connected with a to-be-measured structure, the lower conductive flat plate is connected with the fixed end, and when the two conductive flat plates relatively displace, capacitance formed by the two conductive flat plates changes, so that the resonant frequency of the LC resonant circuit changes, and a mapping relation exists between the resonant frequency and displacement; the LC resonance circuit wirelessly transmits a resonance signal carrying displacement information, and the receiving circuit receives the resonance signal and analyzes the frequency to obtain the displacement information.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a real-time self-driven wireless sensor based on a triboelectric nanogenerator, which is especially suitable for real-time monitoring of vibration and displacement of civil engineering structures (such as bridges, dams, high-rise buildings, railway tracks, etc.), and belongs to the interdisciplinary field of self-driven sensing and structural health monitoring. Background Technology

[0002] Under the influence of environmental and external loads such as wind loads, traffic loads, temperature and humidity changes, and earthquakes, civil engineering structures (such as bridges, dams, high-rise buildings, and railway tracks) will experience vibration and displacement. When the displacement exceeds the design threshold, it will directly affect the normal use of the structure and may even lead to safety accidents such as structural cracking and collapse. Therefore, real-time and accurate monitoring of the displacement of civil engineering structures is a key means to ensure the safe service of the structure.

[0003] Currently, mainstream displacement monitoring technologies mainly rely on strain measurement instruments, including dial gauges, resistance strain gauges, and vibrating wire sensors, but these technologies have the following significant drawbacks:

[0004] Reliance on external power supply: Existing sensors require an external power supply or built-in battery. In the monitoring of large-scale civil engineering structures, wiring is cumbersome, batteries need to be replaced regularly, and maintenance costs are high.

[0005] Poor measurement accuracy and anti-interference: The output signal of the resistance strain gauge is weak and nonlinear, and it is easily affected by temperature, humidity and electromagnetic interference. Moreover, it can only measure the strain of a single point on the surface of the component along a certain direction and cannot perform global measurement. The vibrating wire sensor has strict requirements for materials and processing technology, and the measurement accuracy can only reach the millimeter level, which is difficult to meet the needs of monitoring small displacements.

[0006] Installation and application scope are limited: Dial gauge strain gauges are limited by the length of the markings and the installation space, making them unsuitable for complex structures; some sensors have complex structures and high costs, making it difficult to promote and apply them on a large scale.

[0007] Poor environmental adaptability: In outdoor monitoring, humidity, temperature difference, rain and snow can easily cause sensor failure and shorten its service life.

[0008] To address the aforementioned technical problems, this invention proposes a real-time self-driven wireless sensor based on a triboelectric nanogenerator. This sensor achieves self-powering through the triboelectric nanogenerator and enables precise wireless displacement monitoring by combining the capacitance-frequency mapping relationship, thus filling a gap in existing technologies. Summary of the Invention

[0009] To address the shortcomings of the aforementioned background technology, this invention proposes a real-time self-driven wireless sensor based on a triboelectric nanogenerator, which solves the technical problems of existing displacement monitoring sensors that rely on external power sources, have low measurement accuracy, weak anti-interference capabilities, cumbersome installation and wiring, limited applicability, and cannot achieve full-area measurement.

[0010] The technical solution of this invention is as follows:

[0011] A real-time self-driven wireless sensor based on a triboelectric nanogenerator includes a triboelectric nanogenerator, a discharge device, a sliding capacitive displacement sensor, an inductor coil, and a receiving circuit. The sliding capacitive displacement sensor and the inductor coil form a parallel LC resonant circuit, and the triboelectric nanogenerator supplies power to the LC resonant circuit through the discharge device. The sliding capacitive displacement sensor includes an upper conductive plate and a lower conductive plate arranged opposite to each other, and at least one dielectric material layer located between the upper and lower conductive plates. The upper conductive plate is connected to the structure under test, and the lower conductive plate is connected to a fixed end. When the two conductive plates are displaced relative to each other, the capacitance formed changes, which in turn causes the resonant frequency of the LC resonant circuit to change. There is a mapping relationship between the resonant frequency and the displacement. The LC resonant circuit wirelessly transmits a resonant signal carrying displacement information, and the receiving circuit receives the resonant signal and analyzes the frequency to obtain the displacement information.

[0012] The above technical solution is the core solution of this invention: it includes a triboelectric nanogenerator, a discharge device, a sliding capacitive displacement sensor, an inductor coil, and a receiving circuit; the sliding capacitive displacement sensor and the inductor coil form a parallel LC resonant circuit, and the triboelectric nanogenerator supplies power to the LC resonant circuit through the discharge device; the upper conductive plate is connected to the structure under test, and the lower conductive plate is connected to the fixed end; the displacement causes a change in capacitance, which in turn changes the resonant frequency; and the displacement information is obtained through wireless transmission and frequency analysis.

[0013] Beneficial effects:

[0014] Completely solves the problem of dependence on external power supply and realizes self-driven monitoring: It collects environmental mechanical energy (such as structural vibration, kinetic energy driven by wind load, etc.) through triboelectric nanogenerator and converts it into electrical energy to power the entire sensing system. No external power supply or built-in battery is required, avoiding the problems of cumbersome wiring and regular battery replacement in large-scale civil engineering monitoring, and greatly reducing maintenance costs and workload.

[0015] Improved measurement accuracy and anti-interference capability: Displacement monitoring is achieved by using capacitance-frequency mapping relationship. Compared with the weak signal output of resistance strain gauge, the resonant frequency signal is stronger and has better linearity. At the same time, the frequency signal of LC resonant circuit is far less affected by temperature, humidity and electromagnetic interference than the resistance strain signal, and the measurement stability is significantly improved.

[0016] Simplified installation process and expanded application scope: The sliding capacitive displacement sensor has a simple structure and flexible assembly method for the upper and lower conductive plates. It does not require strict restrictions on installation space and marking length, and can be adapted to the monitoring needs of complex civil engineering structures such as bridges and dams, making it easy to promote on a large scale.

[0017] Achieving wireless monitoring and overcoming wiring limitations: The LC resonant circuit wirelessly transmits resonant signals carrying displacement information, which are remotely received and analyzed by the receiving circuit. This eliminates the need to lay a large number of signal transmission lines on large structures, reducing installation difficulty and engineering costs. It is especially suitable for monitoring civil engineering projects in remote areas or complex terrains.

[0018] Providing a foundation for micro-displacement monitoring: The capacitive displacement sensing principle is highly sensitive to displacement changes. Compared with the millimeter-level accuracy of vibrating wire sensors, it can achieve higher precision displacement measurement, meet the needs of early micro-deformation monitoring of civil engineering structures, and provide early warning of potential structural safety hazards.

[0019] Based on the above technical solutions, as a preferred technical solution for the real-time self-driven wireless sensor based on triboelectric nanogenerators, the triboelectric nanogenerator is any one of the following: rotating, sliding, vertical contact separation, or independent triboelectric layer mode, used to collect environmental mechanical energy and convert it into electrical energy.

[0020] Beneficial effects:

[0021] Improving the efficiency of environmental mechanical energy harvesting: Different modes of triboelectric nanogenerators are adapted to different types of mechanical energy forms. For example, the rotary type is suitable for rotational motion driven by structural vibration, the sliding type is suitable for linear sliding displacement of structures, the vertical contact separation type is suitable for vertical vibration of structures, and the independent friction layer mode is suitable for irregular vibration forms. The optimal type can be selected according to the specific monitoring scenario (such as beam vibration of bridges, dam settlement of dams, and train load vibration of railway tracks) to maximize energy harvesting efficiency and ensure stable power supply to the sensing system.

[0022] Enhanced system adaptability and flexibility: Multiple types of sensors allow them to be adapted to the vibration characteristics of different civil engineering structures, avoiding the problem of insufficient energy harvesting by a single type of generator in specific scenarios, expanding the applicability of the sensors and improving their practicality in complex engineering environments.

[0023] Reduced customization costs: For different monitoring scenarios, there is no need to redesign the core structure of the generator; only the corresponding mode needs to be selected, which simplifies the sensor customization process and reduces the cost of large-scale application.

[0024] Based on the above technical solutions, as a preferred technical solution for the real-time self-driven wireless sensor based on triboelectric nanogenerator, the discharge device is a gas discharge tube, a needle-needle discharge device, a needle-plate discharge device, or a plate-plate discharge device.

[0025] Beneficial effects:

[0026] Ensuring power supply stability and safety: The electrical energy output by the triboelectric nanogenerator may experience voltage fluctuations. The discharge device can stabilize and limit the electrical energy to ensure a stable power supply voltage for the LC resonant circuit, avoid voltage fluctuations that cause resonant frequency drift, and improve measurement accuracy. At the same time, the discharge device can prevent overvoltage from damaging circuit components and extend the sensor's service life.

[0027] Adaptable to different energy output scenarios: Different types of discharge devices have different discharge characteristics and voltage adaptation ranges. For example, gas discharge tubes are suitable for high-voltage stable discharge, while needle-needle discharge devices are suitable for low-voltage and low-current scenarios. The appropriate discharge device can be selected according to the output characteristics of the triboelectric nanogenerator (such as output voltage and current magnitude) to further optimize power supply stability.

[0028] Improved environmental adaptability: Some discharge devices (such as gas discharge tubes) have good temperature and humidity resistance and corrosion resistance, and can work stably in outdoor humid environments with large temperature differences, solving the problem that existing sensors are prone to failure in harsh environments.

[0029] Based on the above technical solution, as a preferred technical solution for the real-time self-driven wireless sensor based on triboelectric nanogenerator, the dielectric material layer is one or a combination of two of polytetrafluoroethylene, polyimide, polydimethylsiloxane, polypropylene, or polystyrene; the lower surface of the upper conductive plate is in close contact with dielectric material layer one, and the upper surface of the lower conductive plate is in close contact with dielectric material layer two; the thicknesses of dielectric material layer one and dielectric material layer two are d1 and d2, respectively, and their dielectric constants are ε. r1 and ε r1 .

[0030] Beneficial effects:

[0031] Improving capacitance measurement accuracy: The selected dielectric materials all have excellent insulation properties and stable dielectric constants, which can reduce dielectric loss, ensure the linearity of capacitance value changes with displacement, and avoid measurement errors caused by unstable dielectric material performance; when the two materials are used in combination, the sensitivity of the capacitor to displacement can be optimized by adjusting the dielectric constant and thickness parameters, further improving the accuracy of monitoring small displacements.

[0032] Enhanced environmental adaptability: Materials such as polytetrafluoroethylene and polyimide have excellent resistance to high and low temperatures, moisture, and corrosion, enabling them to work stably in harsh outdoor environments for extended periods. This prevents the dielectric materials from becoming damp or aging, which could lead to sensor failure and extend the sensor's lifespan.

[0033] Reduced processing and assembly difficulty: The selected dielectric materials are easy to process into thin sheet structures, have good adhesion to conductive plates, and the assembly process is simple. This ensures close contact between the upper and lower conductive plates and the dielectric material layer, reduces measurement errors caused by contact gaps, and lowers production and manufacturing costs.

[0034] Based on the above technical solution, as a preferred technical solution for the real-time self-driven wireless sensor based on triboelectric nanogenerator, the upper and lower conductive plates are made of one of copper, aluminum, iron, silver, or conductive graphite. The plates are l in size and w in width. The initial distance between the upper and lower conductive plates is consistent with the thickness of the dielectric material layer.

[0035] Beneficial effects:

[0036] Ensuring conductivity and measurement stability: The selected materials all have excellent conductivity, which can reduce the influence of electrode resistance on capacitance signals and ensure that capacitance changes can accurately reflect displacement changes; at the same time, metals such as copper and aluminum have good mechanical strength, while conductive graphite has good flexibility, which can be selected according to the structural characteristics of the monitoring scenario to avoid measurement errors caused by electrode deformation.

[0037] Cost reduction and economic efficiency: Materials such as aluminum and copper are relatively inexpensive, while conductive graphite is easy to process. Compared with precious metal electrodes, they can significantly reduce the manufacturing cost of sensors and facilitate large-scale application. Clear dimensional parameters standardize electrode processing and improve production efficiency.

[0038] Optimize initial capacitance stability: The initial spacing is consistent with the thickness of the dielectric material layer, which can ensure the stability of the initial capacitance value of the sensor, avoid zero drift caused by initial capacitance deviation, improve measurement accuracy, and reduce debugging workload.

[0039] Based on the above technical solution, as a preferred technical solution for the real-time self-driven wireless sensor based on triboelectric nanogenerator, the inductance value L of the inductor coil is 1μH-10mH, the resonant frequency range of the LC resonant circuit is 1MHz-100MHz; the receiving circuit includes a receiving LC resonator, a signal amplifier, a filter, and a fast Fourier transform (FFT) module, and the resonant frequency of the receiving LC resonator is matched with that of the transmitting LC resonant circuit.

[0040] Beneficial effects:

[0041] Improved wireless transmission performance: Optimized inductance value and resonant frequency range ensure that the resonant signal has a good wireless transmission distance and anti-interference capability. The frequency range of 1MHz-100MHz is suitable for short and medium distance civil engineering monitoring (such as bridge span, dam body range), avoiding excessive signal attenuation; frequency matching between the receiver and transmitter can improve signal reception efficiency and reduce signal loss.

[0042] Improving signal analysis accuracy: The signal amplifier in the receiving circuit can enhance weak received signals, the filter can filter out environmental interference signals, and the FFT module can quickly and accurately analyze the resonant frequency. Compared with traditional frequency analysis methods, it has higher accuracy and faster response speed, enabling real-time displacement monitoring.

[0043] Enhanced system compatibility and standardization: Clearly defined inductance values ​​and frequency ranges standardize the selection of inductors, and the modular design of the receiving circuit (amplifier, filter, FFT module) facilitates mass production and maintenance, reducing the difficulty and cost of system integration.

[0044] Based on the above technical solution, as a preferred technical solution for the real-time self-driven wireless sensor based on triboelectric nanogenerator, the triboelectric nanogenerator includes, from top to bottom, a bottom rigid substrate, a fan-shaped electrode layer, a bottom dielectric material layer, a rotating shaft, an upper dielectric material layer, a top rigid substrate, and fan blades. The fan-shaped electrode layer is connected to the upper conductive plate through a discharge device, and the bottom rigid substrate is connected to the lower conductive plate.

[0045] Beneficial effects:

[0046] Improved energy harvesting efficiency: The combination of the fan-shaped electrode layer and the upper and lower dielectric material layers can drive the top rigid substrate and the upper dielectric material layer to rotate through the fan blades, so that the upper and lower dielectric material layers and the fan-shaped electrode layer produce frequent contact-separation or sliding friction, maximizing the triboelectric efficiency and improving the power output; the rotating shaft structure ensures smooth rotation and reduces mechanical loss.

[0047] Enhanced structural stability and integration: The rigid substrate provides stable support for all components of the generator, preventing component displacement or deformation in a vibrating environment; the electrodes of the generator and displacement sensor are directly connected, simplifying circuit connections, improving system integration, and reducing line losses and fault points.

[0048] Adaptable to vibration energy harvesting scenarios: The fan blade structure can be directly driven to rotate by wind load or structural vibration without the need for an additional power conversion mechanism. It is suitable for scenarios such as bridges and high-rise buildings that are greatly affected by wind and vibration, further improving the environmental adaptability of the sensor.

[0049] Based on the above technical solution, as a preferred technical solution for the real-time self-driven wireless sensor based on triboelectric nanogenerator, the expression for its capacitance when the upper and lower conductive plates are displaced is: (1).

[0050] Where d0=d1 / ε r1 +d2 / ε r2 ε0 represents the effective thickness of the dielectric material, l represents the length of the plate electrode when the displacement x=0, w represents the width of the conductive plate, and ε0 represents the vacuum dielectric constant.

[0051] The expression for the resonant frequency of an LC circuit is: (2).

[0052] Where L is the inductance of the inductor coil, and f(t) is the resonant frequency.

[0053] Combining equations (1) and (2), we obtain that there is a mapping relationship between f(t) and x(t) at a certain time t: f(t) → x(t). That is, at a certain time t, by measuring the resonant frequency f(t), we can obtain the displacement x(t) at this moment, and transmit the signal wirelessly through the LC resonant circuit; by receiving the resonant signal through the signal receiving circuit, we can obtain the displacement by analyzing the frequency of the resonant signal.

[0054] Beneficial effects:

[0055] Improving measurement accuracy and theoretical support: Quantitative mathematical expressions provide a clear theoretical basis for displacement measurement, avoiding errors caused by empirical formulas; through precise formula calculations, frequency measurement errors can be converted into displacement measurement errors, making it easier to improve displacement measurement accuracy by optimizing frequency measurement accuracy, and achieving high-precision monitoring of ≤0.1mm.

[0056] Real-time and rapid monitoring is achieved: The mapping relationship is simple and direct, without the need for complex signal processing algorithms. The receiving circuit can quickly calculate the displacement based on the measured resonant frequency, thereby improving the monitoring response speed and meeting the needs of real-time monitoring of civil engineering structures (such as rapid displacement response under sudden loads such as earthquakes and strong winds).

[0057] Simplified system debugging and calibration: The clear mathematical model makes the sensor calibration process simpler. Calibration can be completed simply by calibrating the correspondence between frequency and displacement using a standard displacement platform, which reduces the debugging difficulty and workload.

[0058] Based on the above technical solution, the preferred technical solution for the real-time self-driven wireless sensor based on triboelectric nanogenerator further includes global displacement measurement: the real-time self-driven wireless sensor based on triboelectric nanogenerator is configured as a global monitoring unit consisting of a lateral displacement sensor (DS-x) and a side displacement sensor (DS-y). The moving part of the lateral displacement sensor (DS-x) moves along the x-direction, i.e., along the length l of the plate electrode. The displacement change alters the overlap area of ​​the two electrodes along the x-direction, resulting in a change in capacitance. The moving part of the side displacement sensor (DS-y) moves along the y-direction, i.e., along the width w of the plate electrode. The change alters the overlap area of ​​the two electrodes along the y-direction, resulting in a change in capacitance. The two sensors, each with its own inductor coil, form independent parallel LC resonant circuits, sharing the same triboelectric nanogenerator power supply and the same receiving circuit. The lower conductive plates of both sensors are rigidly connected to the fixed end, and the upper conductive plates are connected to the same monitoring point of the structure under test. The capacitance change of each sensor is converted into a change in the resonant frequency of its respective LC resonant circuit. After receiving the resonant signals from the two sensors, the receiving circuit analyzes the frequencies and calculates the displacement data in the x and y directions based on the corresponding frequency-displacement mapping relationship. Then, the total displacement information of the monitoring point in the xy plane is obtained through coordinate synthesis.

[0059] Beneficial effects:

[0060] Breaking through the limitations of existing technologies in full-range measurement: Existing sensors can mostly only measure displacement in a single direction and cannot reflect complex structural deformations (such as the torsion of bridge beams and the horizontal and vertical deformation of dam bodies). This solution uses a combination of sensors in the x and y directions to achieve full-range displacement monitoring of monitoring points in a plane, more comprehensively reflecting the structural deformation state and improving the accuracy of safety warnings.

[0061] Improved system economy and integration: The two sensors share the same triboelectric nanogenerator and receiving circuit, eliminating the need for separate power supply and receiving systems for each direction, thus reducing equipment costs and installation complexity; The two sensors at the same monitoring point work synchronously, enabling synchronous acquisition of displacement data and ensuring the accuracy of coordinate synthesis.

[0062] Enhanced monitoring flexibility: The installation angle and position of the sensors in the x and y directions can be flexibly configured according to specific monitoring needs, adapting to the deformation characteristics of different structures (such as monitoring the lateral and vertical displacement of railway tracks), thus expanding the applicability of the sensors.

[0063] Based on the above technical solution, the preferred technical solution for the real-time self-driven wireless sensor based on triboelectric nanogenerator is applied to displacement monitoring of bridges, dams, high-rise buildings or railway tracks. The displacement measurement range of the structure under test is 0-50cm, and the measurement accuracy is ≤0.1mm.

[0064] Beneficial effects:

[0065] Precisely matching the monitoring needs of civil engineering: The measurement range of 0-50cm covers the normal deformation range of most civil engineering structures (such as the beam deflection of bridges, the settlement of dams, and the wind-induced displacement of high-rise buildings), and the accuracy of ≤0.1mm meets the needs of early monitoring of small deformations in structures, which can detect potential structural safety hazards in advance and avoid accidents.

[0066] Enhancing the practicality and operability of technical solutions: Clear application scenarios and parameters make the design and manufacturing of sensors more targeted, making it easier for users to select and use them according to specific engineering needs, thus lowering the application threshold; at the same time, clear accuracy indicators provide standards for sensor performance testing, facilitating quality control and acceptance.

[0067] Enhance marketability: Precisely positioned in the field of structural health monitoring for civil engineering, the clearly defined applicable scenarios and performance parameters allow users to quickly determine whether the sensor meets their needs, thereby increasing market acceptance and facilitating large-scale promotion and application.

[0068] This invention relates to a real-time self-driven wireless sensor based on a triboelectric nanogenerator. Through the synergistic optimization of multiple technical solutions, it comprehensively solves the core defects of existing displacement monitoring sensors for civil engineering structures, and has the following overall beneficial effects:

[0069] Achieving self-powered wireless monitoring and completely eliminating dependence on external power sources: By efficiently collecting environmental mechanical energy and converting it into electrical energy through triboelectric nanogenerators, the sensing system is stably powered without the need for external power sources or regular battery replacements. Combined with wireless signal transmission, it greatly simplifies the wiring process for monitoring large-scale civil engineering structures, reduces installation and maintenance costs, and is especially suitable for engineering monitoring scenarios in remote and complex terrains.

[0070] To improve measurement accuracy and stability and meet the needs of micro-displacement monitoring: The system adopts the monitoring principle of capacitance-frequency mapping, combined with optimized dielectric materials, conductive electrodes and signal analysis modules, to achieve a displacement measurement accuracy of ≤0.1mm, far exceeding the millimeter-level accuracy of traditional vibrating wire sensors; at the same time, the system has strong resistance to temperature and humidity and electromagnetic interference, good signal linearity, and can achieve long-term stable monitoring, providing reliable data support for early warning of structural safety hazards.

[0071] Achieving full-domain displacement monitoring and comprehensively reflecting the structural deformation state: Through the combined design of displacement sensors in the x and y directions, the limitation of existing sensors measuring in a single direction is broken, enabling the collection of full-domain displacement information of monitoring points in the plane, reflecting the complex deformation state of structures such as bridges and dams more comprehensively and accurately, and improving the comprehensiveness and reliability of safety monitoring.

[0072] Enhanced environmental adaptability and applicability: By selecting weather-resistant materials and optimizing generator structure and discharge device, the sensor can work stably for a long time in harsh outdoor environments with high humidity, large temperature differences, and frequent vibrations. At the same time, the adaptable design of multiple types of generators and discharge devices can meet the monitoring needs of different civil engineering structures such as bridges, dams, high-rise buildings, and railway tracks, making it widely applicable.

[0073] Simple structure, low cost, and easy to promote on a large scale: All components of the sensor adopt standardized and easy-to-process materials and structures, with high system integration and low manufacturing cost; the installation process is simple and does not require complicated debugging procedures, which can significantly reduce the overall cost of engineering monitoring, making it easy to promote and apply on a large scale in the field of civil engineering, and filling the gap in existing self-driven full-domain displacement monitoring technology. Attached Figure Description

[0074] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0075] Figure 1 This is a schematic diagram of the structure of the present invention.

[0076] Figure 2 This is a circuit diagram of the present invention.

[0077] Figure 3 It is a discharge voltage curve of the discharge device.

[0078] Figure 4 This invention relates to the capacitance under different displacements (the ratio of displacement to the length of the plate electrode).

[0079] Figure 5 This is the resonant waveform diagram of the transmitter and receiver when x / l = 1 / 2.

[0080] Figure 6 It is the frequency domain diagram obtained by performing a Fast Fourier Transform (FFT) on the transmitter and receiver when x / l=1 / 2.

[0081] Figure 7 These are the resonant frequencies of the receiver corresponding to different x / l values.

[0082] Explanation of icon numbers:

[0083] 1. Bottom rigid substrate, 2. Fan-shaped electrode layer, 3. Dielectric material layer, 4. Rotating shaft, 5. Dielectric material layer, 6. Top rigid substrate, 7. Fan blade, 8. Upper conductive plate, 9. Lower conductive plate.

[0084] GDT is a gas discharge tube, L1 is inductor coil one, L2 is inductor coil two, and C2 is a fixed capacitor. Detailed Implementation

[0085] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the core concept of the present invention and the following embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0086] These embodiments are provided to make the application thorough and complete, and to fully express the scope of the application to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions, and values ​​illustrated in these embodiments should be interpreted as merely exemplary and not as limiting.

[0087] It should be noted that, in the description of this application, unless otherwise stated, "several" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "axial," "radial," etc., indicating orientation or positional relationships are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0088] Furthermore, the terms "first," "second," and similar terms used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. "Vertical" is not strictly vertical, but within the permissible margin of error. "Parallel" is not strictly parallel, but within the permissible margin of error. Terms such as "including" or "contains" mean that the element preceding the word encompasses the element listed after it, and do not exclude the possibility of encompassing other elements as well.

[0089] It should also be noted that, in the description of this application, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application depending on the specific circumstances. When a specific device is described as being located between a first device and a second device, an intermediary device may or may not be present between the specific device and the first or second device.

[0090] All terms used in this application have the same meaning as understood by one of ordinary skill in the art to which this application pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein.

[0091] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0092] A real-time self-driven wireless sensor based on triboelectric nanogenerators, such as Figures 1 to 7 As shown, the device includes a triboelectric nanogenerator, a discharge device (GDT), a sliding capacitive displacement sensor, an inductor coil (L1), an inductor coil (L2), and a receiving circuit. The sliding capacitive displacement sensor and the inductor coil form a parallel LC resonant circuit. The triboelectric nanogenerator supplies power to the LC resonant circuit through the discharge device. The sliding capacitive displacement sensor includes an upper conductive plate 8 and a lower conductive plate 9 arranged opposite each other, and at least one dielectric material layer located between the upper conductive plate 8 and the lower conductive plate 9. The upper conductive plate 8 is connected to the structure under test, and the lower conductive plate 9 is connected to a fixed end. When the two conductive plates are displaced relative to each other, the capacitance they form changes, which in turn causes the resonant frequency of the LC resonant circuit to change. There is a mapping relationship between the resonant frequency and the displacement. The LC resonant circuit wirelessly transmits a resonant signal carrying displacement information. The receiving circuit receives the resonant signal and analyzes the frequency to obtain the displacement information.

[0093] Preferably, the triboelectric nanogenerator is any one of the following: rotary, sliding, vertical contact separation, or independent triboelectric layer mode, used to collect environmental mechanical energy and convert it into electrical energy.

[0094] Based on the above technical solutions, as a preferred technical solution for the real-time self-driven wireless sensor based on triboelectric nanogenerator, the discharge device is a gas discharge tube, a needle-needle discharge device, a needle-plate discharge device, or a plate-plate discharge device.

[0095] Preferably, the dielectric material layer is one or a combination of two of the following: polytetrafluoroethylene, polyimide, polydimethylsiloxane, polypropylene, polyvinyl chloride, polyethylene, polyvinylidene chloride, polypropylene hydrocarbon, rubber, polyester, polyvinyl alcohol, cellulose acetate, polyvinyl alcohol, nylon, ethyl cellulose, or polystyrene; the lower surface of the upper conductive plate 8 is in close contact with the first dielectric material layer, and the upper surface of the lower conductive plate 9 is in close contact with the second dielectric material layer. The thicknesses of the first dielectric material layer and the second dielectric material layer are d1 and d2, respectively, and their dielectric constants are ε. r1 and ε r2 .

[0096] Preferably, the upper conductive plate 8 and the lower conductive plate 9 are made of one of copper, aluminum, iron, silver, or conductive graphite, the plate is l, the width is w, and the initial distance between the upper conductive plate 8 and the lower conductive plate 9 is consistent with the thickness of the dielectric material layer.

[0097] Preferably, the inductance value L of the inductor coil is 1μH-10mH, and the resonant frequency range of the LC resonant circuit is 1MHz-100MHz; the receiving circuit includes a receiving LC resonator, a signal amplifier, a filter, and a fast Fourier transform (FFT) module, and the resonant frequency of the receiving LC resonator is matched with that of the transmitting LC resonant circuit.

[0098] Preferably, the triboelectric nanogenerator comprises, from top to bottom, a bottom rigid substrate 1, a fan-shaped electrode layer 2, a lower dielectric material layer 3, a rotating shaft 4, an upper dielectric material layer 5, a top rigid substrate 6, and a fan blade 7. The fan-shaped electrode layer 2 is connected to the upper conductive plate 8 through a discharge device, and the bottom rigid substrate 1 is connected to the lower conductive plate 9.

[0099] Preferably, when the upper conductive plate 8 and the lower conductive plate 9 are displaced, the expression for their capacitance is: (1).

[0100] Where d0=d1 / ε r1 +d2 / ε r2 ε0 represents the effective thickness of the dielectric material, l represents the length of the plate electrode when the displacement x=0, w represents the width of the conductive plate, and ε0 represents the vacuum dielectric constant.

[0101] The expression for the resonant frequency of an LC circuit is: (2).

[0102] Where L is the inductance of the inductor coil, and f(t) is the resonant frequency.

[0103] Combining equations (1) and (2), we obtain that there is a mapping relationship between f(t) and x(t) at a certain time t: f(t) → x(t). That is, at a certain time t, by measuring the resonant frequency f(t), we can obtain the displacement x(t) at this moment, and transmit the signal wirelessly through the LC resonant circuit; by receiving the resonant signal through the signal receiving circuit, we can obtain the displacement by analyzing the frequency of the resonant signal.

[0104] Preferably, it also includes global displacement measurement: a global monitoring unit is composed of a lateral displacement sensor (DS-x) and a side displacement sensor (DS-y). The moving part of the lateral displacement sensor (DS-x) moves along the x-direction, i.e., along the length l of the plate electrode. The displacement change causes the overlap area of ​​the two electrodes along the x-direction to change and thus the capacitance changes. The moving part of the side displacement sensor (DS-y) moves along the y-direction, i.e., along the width w of the plate electrode. The displacement change causes the overlap area of ​​the two electrodes along the y-direction to change and thus the capacitance changes. The two sensors are respectively connected to their respective inductors to form independent parallel LC resonant circuits, sharing the same triboelectric nanogenerator power supply and the same receiving circuit. The lower conductive plates of both sensors are rigidly connected to the fixed end, and the upper conductive plates are connected to the same monitoring point of the structure under test. The capacitance change of each sensor is converted into the resonant frequency change of its respective LC resonant circuit. After receiving the resonant signals of the two sensors, the receiving circuit analyzes the frequencies and calculates the displacement data in the x and y directions according to the corresponding frequency-displacement mapping relationship. Then, the global displacement information of the monitoring point in the xy plane is obtained by coordinate synthesis.

[0105] Preferably, it is applied to displacement monitoring of bridges, dams, high-rise buildings or railway tracks, with the displacement measurement range of the structure under test being 0-50cm and the measurement accuracy being ≤0.1mm.

[0106] As a general embodiment of the present invention

[0107] I. Structural Features

[0108] The real-time self-driven wireless sensor based on a triboelectric nanogenerator in this embodiment mainly consists of five parts: a triboelectric nanogenerator, a gas discharge tube (discharge device), a sliding capacitive displacement sensor, an inductor coil, and a receiving circuit. The specific structure is as follows:

[0109] 1. Triboelectric Nanogenerator: Utilizing a rotary structure, the following layers are assembled from top to bottom: a bottom rigid substrate (material: aluminum alloy, dimensions: 100mm × 100mm × 5mm), a fan-shaped electrode layer (material: copper, number of fans: 8, radius of each fan: 40mm, electrode thickness: 0.2mm), and a lower dielectric material layer (material: polytetrafluoroethylene, thickness d2 = 0.5mm, dielectric constant ε). r2=2.1), shaft (material: stainless steel, diameter: 10mm, length: 80mm), upper dielectric material layer (material: polydimethylsiloxane, thickness d1=0.5mm, dielectric constant ε) r1 =3.0), top rigid substrate (material: aluminum alloy, size: 100mm×100mm×5mm), fan blade (material: engineering plastic, quantity: 3 pieces, blade length: 150mm); the fan-shaped electrode layer is connected to the input end of the gas discharge tube through wires, and the bottom rigid substrate is fixedly connected to the lower conductive plate of the sliding capacitive displacement sensor through bolts.

[0110] 2. Discharge device: A gas discharge tube (model: GS-600, rated discharge voltage: 600V, maximum discharge current: 10A) is selected. The input end is connected to the fan-shaped electrode layer of the triboelectric nanogenerator, and the output end is connected to the upper conductive plate of the sliding capacitive displacement sensor. It is used to stabilize the output power of the generator.

[0111] 3. Sliding capacitive displacement sensor: This sensor comprises an upper conductive plate, a lower conductive plate, and two dielectric material layers. The lower surface of the upper conductive plate (material: copper, dimensions: 80mm×50mm×0.2mm) is tightly bonded to the upper dielectric material layer (same as the upper dielectric material layer of the generator, polydimethylsiloxane, d1=0.5mm) using an adhesive. The upper surface of the lower conductive plate (material: copper, dimensions: 80mm×50mm×0.2mm) is tightly bonded to the lower dielectric material layer (same as the lower dielectric material layer of the generator, polytetrafluoroethylene, d2=0.5mm). The upper conductive plate is fixed to the structure under test (e.g., bridge beam) via a connector, and the lower conductive plate is fixed to a fixed end (e.g., bridge bearing) via a rigid base plate. Initially, the upper and lower conductive plates completely overlap, with an initial distance d0=d1 / ε. r1 +d2 / ε r2 =0.5 / 3.0+0.5 / 2.1≈0.397mm.

[0112] 4. Inductor coil: A wire-wound inductor coil (material: enameled copper wire, wire diameter: 0.5mm, number of turns: 100 turns) with an inductance value of L=10μH is selected. It is connected in parallel with the upper and lower conductive plates of the sliding capacitive displacement sensor to form an LC resonant circuit. The output terminal of the resonant circuit is connected to the transmitting antenna (length: 50mm, material: copper).

[0113] 5. Receiving circuit: including a receiving LC resonator (inductance value: 10μH, matched with the transmitting inductor coil), a signal amplifier (model: AD8421, gain: 1000 times), a filter (model: LPF-100MHz, low-pass cutoff frequency: 100MHz), an FFT module (model: STM32H743, sampling frequency: 200MHz), and a data output module (RS485 interface); the receiving circuit receives the resonant signal from the transmitting end through a receiving antenna (length: 50mm, material: copper), and is encapsulated in a waterproof box (size: 150mm×100mm×80mm), placed at a monitoring station within 50m of the transmitting end.

[0114] II. Assembly Relationship

[0115] 1. Assembly of the triboelectric nanogenerator: First, fix the bottom rigid substrate horizontally, and then attach the fan-shaped electrode layer to its surface with adhesive, ensuring that the electrode layer is flat and wrinkle-free; then attach the lower dielectric material layer to the surface of the fan-shaped electrode layer, aligning the edges; the rotating shaft passes through the central hole of the bottom and top rigid substrates and is fixed by bearings to ensure that the rotating shaft can rotate flexibly; attach the upper dielectric material layer to the lower surface of the top rigid substrate, aligning it with the lower dielectric material layer, with the gap controlled within 0.1mm; finally, fix the fan blades to the upper surface of the top rigid substrate, ensuring that the rotation of the fan blades can drive the top rigid substrate and the upper dielectric material layer to rotate synchronously.

[0116] 2. Power supply circuit assembly: The sector-shaped electrode layer of the triboelectric nanogenerator is connected to the input end of the gas discharge tube through a wire, and the output end of the gas discharge tube is connected to the upper conductive plate of the sliding capacitive displacement sensor through a wire; the lower conductive plate is connected to one end of the inductor coil through a wire, and the upper conductive plate is connected to the other end of the inductor coil through a wire, forming a parallel LC resonant circuit; the transmitting antenna is welded to the output end of the LC resonant circuit.

[0117] 3. Displacement sensor assembly: The lower conductive plate is fixed to the bottom rigid substrate with bolts to ensure it is horizontal; the upper conductive plate is fixed to the monitoring point of the structure to be measured through connectors. The position is adjusted so that the upper and lower conductive plates completely overlap in the initial state and the dielectric material layers are in close contact without gaps.

[0118] 4. Receiver circuit assembly: Connect the receiving LC resonator, signal amplifier, filter, FFT module and data output module by soldering them together on a circuit board. Solder the receiving antenna to the input end of the receiving LC resonator. Place the circuit board in a waterproof box and seal it to ensure waterproof and dustproof protection. Connect it to the monitoring computer through an RS485 interface to achieve real-time data display.

[0119] III. Various parameters

[0120] 1. Material parameters: Dielectric constant of polytetrafluoroethylene The dielectric constant ε of polydimethylsiloxane r1 =3.0, vacuum permittivity Copper electrode conductivity Aluminum alloy substrate density resistivity of enameled copper wire .

[0121] 2. Structural parameters: Triboelectric nanogenerator blade length 150mm, fan-shaped electrode radius 40mm; sliding capacitive displacement sensor electrode dimensions. The dielectric material layer thickness is 0.5mm, and the initial spacing d0≈0.397mm; the inductor coil has 100 turns and an inductance value L=10μH.

[0122] 3. Electrical parameters: Gas discharge tube rated discharge voltage 600V, maximum discharge current 10A; LC resonant circuit resonant frequency range 10MHz-50MHz; signal amplifier gain 1000 times, filter cutoff frequency 100MHz, FFT module sampling frequency 200MHz.

[0123] 4. Monitoring parameters: Displacement measurement range 0-50cm, measurement accuracy ≤0.1mm; wireless transmission distance ≤50m; working environment temperature -20℃~60℃, relative humidity ≤95%.

[0124] IV. Working Principle

[0125] 1. Self-powered principle: When the structure under test (such as a bridge) vibrates under wind load or traffic load, it drives the blades of the triboelectric nanogenerator to rotate. The blades drive the top rigid substrate and the upper dielectric material layer to rotate around the axis. Frequent contact-separation and sliding friction occur between the upper dielectric material layer, the lower dielectric material layer, and the fan-shaped electrode layer. According to the triboelectric effect and the principle of electrostatic induction, the fan-shaped electrode layer generates induced charges, forming an alternating current, realizing the conversion of environmental mechanical energy into electrical energy. The converted electrical energy is regulated by the gas discharge tube and then provides a stable power supply for the LC resonant circuit.

[0126] 2. Displacement-Capacitance-Frequency Conversion Principle: When the structure under test undergoes displacement, it causes the upper conductive plate of the sliding capacitive displacement sensor to move with the structure, resulting in a change in the overlap area between the upper and lower conductive plates. According to the capacitance formula... (Where w=50mm is the electrode width, l=80mm is the initial overlap length, and x(t) is the displacement at time t), the capacitance C changes linearly with the displacement x(t); since C and the inductor form a parallel LC resonant circuit, according to the resonant frequency formula... The change in capacitance C will cause the resonant frequency f(t) of the resonant circuit to change synchronously, forming a one-to-one mapping relationship between displacement and frequency.

[0127] 3. Wireless Transmission and Signal Analysis Principle: The LC resonant circuit wirelessly transmits the resonant frequency signal carrying displacement information through the transmitting antenna; after receiving the signal, the receiving antenna of the receiving circuit selects the target frequency signal through the receiving LC resonator; the signal amplifier amplifies the weak signal, and the filter filters out environmental interference signals; the FFT module performs a fast Fourier transform on the processed signal to analyze the resonant frequency f(t); according to the preset frequency-displacement mapping relationship (derived by combining the formulas of C and x(t), and f(t) and C), the displacement x(t) at time t is calculated; finally, the displacement data is transmitted to the monitoring computer through the data output module to achieve real-time monitoring.

[0128] V. Instructions for Use

[0129] 1. Installation preparation: Based on the monitoring requirements of the structure to be tested (such as a bridge), select monitoring points (such as the mid-span of the beam or near the supports), clean the surface of the monitoring points to ensure that they are flat and dry; prepare installation tools (bolts, wrenches, adhesives, etc.) and protective equipment.

[0130] 2. Sensor Installation: Fix the bottom rigid plate of the triboelectric nanogenerator to the fixed end (such as the concrete foundation of a bridge bearing) with expansion bolts to ensure a firm fixation; fix the upper conductive plate of the sliding capacitive displacement sensor to the monitoring point of the structure under test with connectors, and adjust the position so that the upper and lower conductive plates are completely overlapped in their initial state; fix the waterproof box of the receiving circuit to the monitoring station (such as a bridge observation station), ensuring that the receiving antenna faces the transmitting antenna and the distance between them is ≤50m.

[0131] 3. System debugging: Connect the receiving circuit to the monitoring computer and open the monitoring software; manually induce a small displacement in the structure under test (e.g., use a jack to lift the beam), observe whether the monitoring software can display the displacement data in real time, and check the data accuracy (calibrated using a standard displacement gauge); adjust the amplifier gain and filter parameters of the receiving circuit to ensure a stable and interference-free signal.

[0132] 4. Formal Monitoring: After commissioning, start the system for long-term real-time monitoring; the monitoring software records displacement data in real time, and automatically issues an early warning signal when the displacement exceeds the preset threshold (such as the allowable displacement value set according to the structural design specification); regularly check the fixing and working status of the sensors to ensure long-term stable operation.

[0133] Preferably, an embodiment based on global displacement measurement

[0134] 1. Structural features: Includes a lateral displacement sensor (DS-x) and a side displacement sensor (DS-y), both of which are sliding capacitive types; the electrode length direction of DS-x is along the x-axis (lateral direction of the structure), and the electrode length direction of DS-y is along the y-axis (lateral direction of the structure); both share the same rotary triboelectric nanogenerator (consistent with the general embodiment) and receiving circuit; the lower conductive plates of DS-x and DS-y are rigidly connected to the fixed end, and the upper conductive plates are connected to the same monitoring point of the structure under test through connectors; the receiving circuit is equipped with a signal switching module to realize time-division analysis of the frequency signals of the two sensors.

[0135] 2. Assembly Relationship: The upper conductive plates of DS-x and DS-y are fixed at the same monitoring point by cross connectors to ensure that displacement in both directions can drive the corresponding electrodes to move; the signal switching module of the receiving circuit is connected to the transmitting end of the two LC resonant circuits, and the switching frequency is 100Hz; the remaining assembly steps are the same as in the general embodiment.

[0136] 3. Key parameters: The measurement range in both the x and y directions is 0-50cm, with an accuracy of ≤0.1mm; the signal switching frequency is 100Hz to ensure the synchronization of displacement data; the coordinate synthesis error is ≤0.15mm; and the wireless transmission distance is ≥90m.

[0137] 4. Working Principle: When the monitoring point generates planar displacement, it simultaneously drives the upper conductive plates of DS-x and DS-y to move. The capacitance of the two sensors changes with the displacement in the x and y directions, respectively, generating two resonant signals of different frequencies. The receiving circuit receives the two signals in a time-division manner through a signal switching module, analyzes the frequency values ​​in the x and y directions, and calculates the displacement in the x and y directions based on their respective frequency-displacement mapping relationships. Through a coordinate synthesis algorithm, the global displacement information of the monitoring point in the xy plane (such as displacement magnitude and direction) is obtained.

[0138] Preferably, an embodiment based on railway track displacement monitoring

[0139] 1. Structural Features: Adapted for railway track monitoring, the triboelectric nanogenerator is sliding (aligned with the track vibration direction), and the discharge device is a plate-to-plate discharge device (plate spacing 10mm); the sliding capacitive displacement sensor has a measurement range of 0-20cm (normal displacement range of railway track) and a measurement accuracy of ≤0.1mm; the receiving circuit is installed in the monitoring box next to the track, with a wireless transmission distance of ≤30m; the sensor as a whole is waterproof and corrosion-resistant encapsulated (protection level IP67).

[0140] 2. Assembly Relationship: The triboelectric nanogenerator and displacement sensor are fixed between the track fastener and the concrete sleeper. The upper conductive plate is connected to the track rail, and the lower conductive plate is fixed to the sleeper. The monitoring box of the receiving circuit is fixed next to the sleeper to ensure stable signal reception. The remaining assembly steps are the same as in the general embodiment.

[0141] 3. Key parameters: Operating ambient temperature -30℃~70℃, impact load resistance ≥100N; measurement range 0-20cm, accuracy ≤0.1mm; response time ≤1ms (adapting to rapid displacement when trains pass); wireless transmission frequency 433MHz (compliant with railway communication standards).

[0142] 4. Working principle: When a train passes by, the track vibrates and displaces, which drives the sliding friction nanogenerator to generate electrical energy. The energy is then regulated by the plate-to-plate discharge device before being supplied to the track. The track displacement causes the conductive plate on the sensor to move, and the capacitance and resonant frequency change. The receiving circuit quickly analyzes the frequency and calculates the displacement. The monitoring software monitors the track displacement in real time and issues an early warning when the displacement exceeds the allowable value (e.g., 3mm).

[0143] 5. Usage method: During installation, ensure that the sensor is tightly connected to the track to avoid loosening due to train vibration; regularly check the waterproof and corrosion-resistant properties of the encapsulation to adapt to the harsh outdoor environment of the railway; during debugging, focus on testing the response speed under rapid displacement to ensure that displacement data is not lost when the train passes; the rest of the usage method is the same as the general embodiment.

[0144] Usage method: During installation, ensure that the electrode directions of DS-x and DS-y are precisely aligned with the x and y axes, respectively; during debugging, calibrate the synchronization of the two sensors to ensure that displacement data are collected simultaneously; the monitoring software is equipped with a global displacement display module to intuitively display the planar displacement trajectory of the monitoring point; the rest of the usage method is the same as the general embodiment.

[0145] All aspects not detailed in this invention are conventional technical means known to those skilled in the art.

[0146] The above content shows and describes the basic principles, main features, and beneficial effects of the present invention. The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A real-time self-driven wireless sensor based on a triboelectric nanogenerator, characterized in that, The device includes a triboelectric nanogenerator, a discharge device, a sliding capacitive displacement sensor, an inductor coil, and a receiving circuit. The sliding capacitive displacement sensor and the inductor coil form a parallel LC resonant circuit, and the triboelectric nanogenerator supplies power to the LC resonant circuit through the discharge device. The sliding capacitive displacement sensor includes an upper conductive plate (8) and a lower conductive plate (9) arranged opposite to each other, and at least one dielectric material layer located between the upper conductive plate (8) and the lower conductive plate (9). The upper conductive plate (8) is connected to the structure under test, and the lower conductive plate (9) is connected to a fixed end. When the two conductive plates are displaced relative to each other, the capacitance formed by them changes, which in turn causes the resonant frequency of the LC resonant circuit to change. There is a mapping relationship between the resonant frequency and the displacement. The LC resonant circuit wirelessly transmits a resonant signal carrying displacement information, and the receiving circuit receives the resonant signal and analyzes the frequency to obtain the displacement information.

2. The real-time self-driven wireless sensor based on a triboelectric nanogenerator according to claim 1, characterized in that, The triboelectric nanogenerator is any one of the following: rotating, sliding, vertical contact separation, or independent triboelectric layer mode, used to collect environmental mechanical energy and convert it into electrical energy.

3. The real-time self-driven wireless sensor based on a triboelectric nanogenerator according to claim 1 or 2, characterized in that, The discharge device is a gas discharge tube, a needle-to-needle discharge device, a needle-to-plate discharge device, or a plate-to-plate discharge device.

4. The real-time self-driven wireless sensor based on a triboelectric nanogenerator according to claim 3, characterized in that, The dielectric material layer is one or a combination of two of the following: polytetrafluoroethylene, polyimide, polydimethylsiloxane, polypropylene, polyvinyl chloride, polyethylene, polyvinylidene chloride, polypropylene hydrocarbon, rubber, polyester, polyvinyl alcohol, cellulose acetate, polyvinyl alcohol, nylon, ethyl cellulose, or polystyrene; the lower surface of the upper conductive plate (8) is in close contact with dielectric material layer one, and the upper surface of the lower conductive plate (9) is in close contact with dielectric material layer two. The thicknesses of dielectric material layer one and dielectric material layer two are d1 and d2, respectively, and their dielectric constants are ε. r1 and ε r2 .

5. The real-time self-driven wireless sensor based on a triboelectric nanogenerator according to claim 4, characterized in that, The upper conductive plate (8) and the lower conductive plate (9) are made of one of copper, aluminum, iron, silver, or conductive graphite. The plate is l and the width is w. The initial distance between the upper conductive plate (8) and the lower conductive plate (9) is consistent with the thickness of the dielectric material layer.

6. The real-time self-driven wireless sensor based on a triboelectric nanogenerator according to any one of claims 1-2 and 4-5, characterized in that, The inductance value L of the inductor coil is 1μH-10mH, and the resonant frequency range of the LC resonant circuit is 1MHz-100MHz. The receiving circuit includes a receiving LC resonator, a signal amplifier, a filter, and a fast Fourier transform (FFT) module. The resonant frequency of the receiving LC resonator is matched with that of the transmitting LC resonant circuit.

7. The real-time self-driven wireless sensor based on a triboelectric nanogenerator according to claim 6, characterized in that, The triboelectric nanogenerator comprises, from top to bottom, a bottom rigid substrate (1), a fan-shaped electrode layer (2), a bottom dielectric material layer (3), a rotating shaft (4), an upper dielectric material layer (5), a top rigid substrate (6), and a fan blade (7). The fan-shaped electrode layer (2) is connected to the upper conductive plate (8) through a discharge device, and the bottom rigid substrate (1) is connected to the lower conductive plate (9).

8. The real-time self-driven wireless sensor based on a triboelectric nanogenerator according to claim 7, characterized in that, When the upper conductive plate (8) and the lower conductive plate (9) are displaced, the expression for their capacitance is: （1）； Where d0=d1 / ε r1 +d2 / ε r2 ε0 is the effective thickness of the dielectric material, l is the length of the plate electrode when the displacement x=0, w is the width of the conductive plate, and ε0 is the vacuum dielectric constant. The expression for the resonant frequency of an LC circuit is: (2); Where L is the inductance of the inductor coil, and f(t) is the resonant frequency; Combining equations (1) and (2), we obtain that there is a mapping relationship between f(t) and x(t) at a certain time t: f(t) → x(t). That is, at a certain time t, by measuring the resonant frequency f(t), we can obtain the displacement x(t) at this moment, and transmit the signal wirelessly through the LC resonant circuit; by receiving the resonant signal through the signal receiving circuit, we can obtain the displacement by analyzing the frequency of the resonant signal.

9. The real-time self-driven wireless sensor based on a triboelectric nanogenerator according to claim 8, characterized in that, The system includes global displacement measurement: a real-time self-driven wireless sensor based on a triboelectric nanogenerator is configured as a global monitoring unit consisting of a lateral displacement sensor (DS-x) and a side displacement sensor (DS-y). The moving part of the lateral displacement sensor (DS-x) moves along the x-direction, i.e., along the length l of the plate electrode. The displacement change alters the overlap area of ​​the two electrodes along the x-direction, resulting in a change in capacitance. The moving part of the side displacement sensor (DS-y) moves along the y-direction, i.e., along the width w of the plate electrode. The displacement change also alters the overlap area of ​​the two electrodes along the y-direction, resulting in a change in capacitance. Each sensor forms an independent parallel LC resonant circuit with its respective inductor coil, sharing the same triboelectric nanogenerator power supply and the same receiving circuit. The lower conductive plates of both sensors are rigidly connected to the fixed end, and the upper conductive plates are connected to the same monitoring point of the structure under test. The capacitance change of each sensor is converted into the resonant frequency change of its respective LC resonant circuit. After receiving the resonant signals from the two sensors, the receiving circuit analyzes the frequencies and calculates the displacement data in the x and y directions according to the corresponding frequency-displacement mapping relationship. Finally, the global displacement information of the monitoring point in the xy plane is obtained through coordinate synthesis.

10. The real-time self-driven wireless sensor based on a triboelectric nanogenerator according to any one of claims 1-2, 4-5, and 7-9, characterized in that, It is used for displacement monitoring of bridges, dams, high-rise buildings or railway tracks. The displacement measurement range of the structure under test is 0-50cm, and the measurement accuracy is ≤0.1mm.

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