A triboelectric-piezoelectric hybrid tuning fork-shaped acoustic nanogenerator

Abstract

The application discloses a triboelectric-piezoelectric hybrid tuning fork-shaped acoustic nanogenerator, which comprises a tapered cavity and a tuning fork-shaped acoustic structure; the output of the tuning fork-shaped acoustic structure is connected with a power management circuit; the tapered cavity is provided with a containing cavity; two tuning fork structures oppositely arranged form a tuning fork structure group; the lengths of the tuning fork structures between the tuning fork structure groups are different; the tuning fork structure is provided with a triboelectric-piezoelectric hybrid structure; the triboelectric-piezoelectric hybrid structure comprises a piezoelectric power generation unit and a triboelectric power generation unit; the piezoelectric power generation unit is arranged at the inner stress area of the tuning fork structure to output a piezoelectric electric signal; the triboelectric power generation unit is arranged at the outer free end of the tuning fork structure to output a triboelectric signal; the power management circuit is connected with an acoustic energy acquisition unit for acquiring the triboelectric signal and the piezoelectric electric signal. The application solves the problems of the existing acoustic energy collection device, such as narrow effective working frequency band, limited single energy conversion mechanism output and insufficient structural integration.

Description

Technical Field

[0001] This invention relates to the field of acoustic energy harvesting and self-powered devices, and in particular to a triboelectric-piezoelectric hybrid tuning fork-shaped acoustic nanogenerator. Background Technology

[0002] With the rapid development of IoT nodes, low-power sensors, and microelectronic devices, the demand for miniaturized, self-powered, and long-term stable power supplies continues to increase. Traditional battery-powered systems suffer from limited lifespan, high maintenance and replacement costs, and the environmental burden of discarded batteries. Therefore, energy harvesting technologies that extract mechanical, thermal, optical, or acoustic energy from the environment and convert it into electrical energy have attracted attention.

[0003] Sound waves and industrial noise are widely present in production equipment, transportation facilities, and enclosed cavity structures. However, acoustic energy typically has characteristics such as limited amplitude, wide frequency distribution, and unstable direction, making it difficult for conventional acoustic energy harvesting devices to maintain effective output over a wide frequency range. Triboelectric nanogenerators typically convert mechanical energy into electrical energy based on triboelectric charging and electrostatic induction, while piezoelectric nanogenerators typically convert mechanical energy into electrical energy based on the polarization charge generated in piezoelectric materials under stress. These two types of nanogenerators have different output characteristics and applicable deformation modes. If they can work synergistically within the same acoustic coupling structure, it will be beneficial to improve the utilization rate of acoustic energy.

[0004] Existing hybrid nanostructures for power generation mostly employ flat plates, thin films, or cantilever beams, and their acoustic wave focusing ability, frequency selectivity, and structural integration still have room for improvement. Tuning fork structures, with their paired strands and well-defined resonant characteristics, can adjust their natural frequencies through strand size, materials, and added mass. Arranging multiple tuning fork structures with different natural frequencies within the same acoustic cavity holds promise for broadband acoustic energy harvesting. However, further improvements are needed to ensure that the triboelectric vibration on the outer side of the tuning fork structure and the piezoelectric deformation on the inner side are generated in parallel after the same flexible response vibration, and that their outputs are stably converged through a power management circuit. Summary of the Invention

[0005] This invention provides a triboelectric-piezoelectric hybrid tuning fork-shaped acoustic nanogenerator to overcome the above-mentioned technical problems.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A triboelectric-piezoelectric hybrid tuning fork-shaped acoustic nanogenerator includes a tapered cavity and a triboelectric-piezoelectric hybrid tuning fork-shaped acoustic structure; and the output of the tuning fork-shaped acoustic structure is connected to a power management circuit. The tapered cavity is provided with a receiving cavity for converging sound waves; The tuning fork-shaped acoustic structure includes several tuning fork structures; Each of the tuning fork structures is arranged at intervals along the axial direction of the cavity, and any two tuning fork structures arranged opposite each other constitute a group of tuning fork structures; the tuning fork structures in the groups of tuning fork structures have different lengths to correspond to different sound frequencies of the sound wave signals input into the cavity. The tuning fork structure is mounted on the mounting base, and the mounting base (3) is suspended and fixed inside the receiving cavity by a pre-set support member; and one end of each tuning fork structure is fixed on the mounting base, and the other end of the tuning fork structure is suspended inside the receiving cavity; the other end of the tuning fork structure is provided with a triboelectric-piezoelectric hybrid structure. The triboelectric-piezoelectric hybrid structure includes a piezoelectric power generation unit and a triboelectric power generation unit; the piezoelectric power generation unit is disposed in the inner force-bearing area of ​​the tuning fork structure; the triboelectric power generation unit is disposed at the outer free end of the tuning fork structure; the triboelectric power generation unit is used to output a triboelectric signal under the vibration condition of the sound wave signal input to the cavity; under the excitation of the sound wave signal input to the cavity, when the tuning fork structure is bent and deformed, the piezoelectric power generation unit generates polarization charge under the piezoelectric effect to output a piezoelectric signal; The power management circuit is used to acquire the acoustic energy of triboelectric and piezoelectric signals.

[0007] Furthermore, the tuning fork structure includes a first fork structure and a second fork structure; One end of the first fork structure and the second fork structure are both located at the fixed point of the mounting base; and in any adjacent tuning fork structures, the first fork structure of one tuning fork structure and the second fork structure of the other tuning fork structure are parallel to each other.

[0008] Furthermore, the piezoelectric power generation unit includes a piezoelectric material layer and a piezoelectric electrode; The bottom surface of the piezoelectric material layer is connected to the top surface of the piezoelectric electrode; the top surface of the piezoelectric material layer is provided with a flexible plate structure; the bottom surface of the piezoelectric electrode is provided with a flexible circuit connection plate.

[0009] Furthermore, the piezoelectric material layer is any one or a combination of lead zirconate titanate piezoelectric ceramic, polyvinylidene fluoride piezoelectric film, and lead magnesium niobate-lead titanate piezoelectric single crystal.

[0010] Furthermore, the triboelectric power generation unit includes a first friction layer, a second friction layer, and friction electrodes respectively disposed corresponding to the first friction layer and the second friction layer; Furthermore, the first friction layer and the second friction layer are formed of materials with different triboelectric sequence positions.

[0011] Furthermore, the material combination of the first friction layer and the second friction layer is any one of polyester and polypropylene, polytetrafluoroethylene and nylon, or polytetrafluoroethylene and fluorinated ethylene propylene copolymer.

[0012] Furthermore, the tapered conical cavity is provided with a sound wave inlet and a sound wave outlet; and the cross-sectional area of ​​the sound wave inlet is larger than the cross-sectional area of ​​the sound wave outlet; the inner wall of the tapered conical cavity is also provided with a sound wave reflection layer for improving the sound pressure coupling efficiency.

[0013] Furthermore, the formula for obtaining the length of the tuning fork structure is as follows:

[0014] In the formula: This represents the first-order approximate natural frequency of the sound wave signal corresponding to the prongs of the tuning fork; The effective length of the tuning fork strands, i.e., the length of the tuning fork structure, is represented by: E; the elastic modulus of the tuning fork structure material; I; the moment of inertia of the tuning fork strands in the tuning fork structure; ρ; the material density of the tuning fork structure; and A; the cross-sectional area of ​​the tuning fork strands in the tuning fork structure.

[0015] Compared with existing technologies, this invention provides a triboelectric-piezoelectric hybrid tuning fork-shaped acoustic nanogenerator, with the following advantages: 1. By focusing sound waves through a tapered converging cavity and selecting frequencies through multiple tuning fork structures, sound waves in different frequency ranges can drive the corresponding tuning fork structures to produce large-amplitude vibrations, which is beneficial to broadening the acoustic energy harvesting frequency band. 2. The piezoelectric power generation unit is set in the inner top force-bearing area of ​​the tuning fork fork, and the triboelectric power generation unit is set at the relatively free end position relative to the outer top of the tuning fork structure. This allows the vibration of the flexible response structure caused by the same acoustic excitation to form piezoelectric deformation on the inner top and triboelectric vibration on the outer top, which are then used in parallel for piezoelectric conversion and triboelectric conversion, thereby improving the utilization rate of the acoustic-mechanical-electric conversion path. 3. The piezoelectric output and triboelectric output are rectified independently and then fed into the power management circuit, which can reduce the impact of the difference in output characteristics between the two types of power generation units on the energy storage node, and facilitate the supply of regulated power to low-power sensors or monitoring nodes. 4. The natural frequency of the tuning fork structure can be adjusted by the length, thickness, width, material, and additional mass blocks of the fork strands, making it easy to customize for different sound source frequency bands such as industrial noise, equipment vibration, or noise from enclosed cavities. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the conical tapered cavity in the triboelectric-piezoelectric hybrid tuning fork acoustic nanogenerator of the present invention; Figure 2 This is a schematic diagram of the end face showing the arrangement of the tapered conical cavity and the multiple tuning fork structures in this embodiment; Figure 3 This is an exploded view of a partial stacked structure of the tuning fork power generation unit in this embodiment; Figure 4 This is a side view of the tuning fork structure in this embodiment; Figure 5 This is a front view of the end of a single tuning fork structure in this embodiment; Figure 6 This is a flowchart of the acoustic wave-driven energy capture method in this embodiment.

[0018] In the diagram: 1. Conical tapered cavity; 11. Acoustic wave inlet; 12. Acoustic wave outlet; 2. Tuning fork structure; 21. First fork structure; 22. Second fork structure; 23. U-shaped gap; 3. Mounting base; 4. Triboelectric power generation unit; 5. Piezoelectric power generation unit; 51. Piezoelectric material layer; 52. Piezoelectric electrode; 53. Flexible plate structure; 54. Flexible circuit connection board. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This embodiment provides a triboelectric-piezoelectric hybrid tuning fork-shaped acoustic nanogenerator, such as Figures 1 to 3 As shown, it includes a tapered conical cavity 1 and a triboelectric-piezoelectric hybrid tuning fork-shaped acoustic structure; and the output of the tuning fork-shaped acoustic structure is connected to a power management circuit; The tapered converging cavity 1 is provided with an acoustic inlet 11 and forms a receiving cavity for converging acoustic waves; the tapered converging cavity 1 is used to converge and guide external acoustic waves into the receiving cavity; specifically, the tapered converging cavity 1 is integrally formed by 3D printing using acrylonitrile-butadiene-styrene copolymer (ABS); the large end diameter of the tapered converging cavity 1 is 120 mm, the small end diameter is 40 mm, the cavity length is 200 mm, and the wall thickness is 2 mm; the tapered converging cavity 1 is provided with an acoustic inlet 11 and an acoustic outlet 12; and the cross-sectional area of ​​the acoustic inlet 11 is larger than the cross-sectional area of ​​the acoustic outlet 12; the inner wall of the tapered converging cavity 1 is also provided with an acoustic wave reflecting layer for improving acoustic pressure coupling efficiency; The tuning fork-shaped acoustic structure includes several tuning fork structures 2; specifically, each tuning fork structure 2 includes a first fork structure 21 and a second fork structure 22; one end of the first fork structure 21 and the second fork structure 22 are jointly disposed at a fixed point position on the mounting base 3, wherein the mounting base 3 can suspend it inside the conical tapered cavity 1 through an external support structure; and in any adjacent tuning fork structures 2, the first fork structure 21 of one tuning fork structure 2 is parallel to the second fork structure of another tuning fork structure 2; specifically, in this embodiment, there are twelve tuning fork structures 2, with each pair of oppositely disposed tuning fork structures 2 forming a group, for a total of six groups; the six groups of tuning fork groups are disposed in the receiving cavity of the conical tapered cavity 1. Inside, and arranged around the central region of the cavity and / or along the axial direction of the tapered cavity 1; each tuning fork group corresponds to the low-frequency, mid-frequency and high-frequency sound wave range respectively, so that the frequency response bandwidth of adjacent tuning fork groups at least partially overlaps, thereby improving the broadband acoustic energy harvesting capability; each tuning fork structure 2 includes a first fork structure 21 and a second fork structure; and the first fork and the second fork extend from the base in the same direction respectively, forming a U-shaped gap 23 between them; in this embodiment, the inherent frequencies of the multiple tuning fork structures 2 are set to cover the preset sound source frequency band, and the frequency response bandwidths corresponding to adjacent inherent frequencies at least partially overlap, so that the acoustic nanogenerator forms broadband acoustic energy harvesting within the preset sound source frequency band; Each of the tuning fork structures 2 is arranged at intervals along the axial direction of the cavity, and any two tuning fork structures 2 arranged opposite each other constitute a group of tuning fork structures. In this embodiment, the two tuning fork structures 2 in each group are arranged opposite each other so as to form relative vibration under sound wave excitation; the lengths of the tuning fork structures 2 in the tuning fork structure groups are different, so as to correspond to different sound frequencies of the sound wave signals input into the cavity. In this embodiment, each tuning fork structure 2 is made of phosphor bronze. The width of the fork strands is 6 mm, the thickness of the fork strands is 1.5-2 mm, the width of the U-shaped gap 23 is 8 mm, and the length of the tuning fork handle is 20 mm. Different tuning fork groups obtain different natural frequencies by changing the length and thickness of the fork strands. For example... Figure 3As shown, six sets of tuning fork structures 2 are arranged at intervals within the receiving cavity of the tapered conical cavity 1, each corresponding to a different sound wave frequency band. In this embodiment, one example parameter is as follows: Set 1, fork length 50 mm, thickness 2 mm, natural frequency 125 Hz, corresponding to low-frequency sound waves; Set 2, fork length 42 mm, thickness 2 mm, natural frequency 180 Hz, corresponding to low-frequency sound waves; Set 3, fork length 35 mm, thickness 1.8 mm, natural frequency 260 Hz, corresponding to mid-frequency sound waves; Set 4, fork length 30 mm, thickness 1.8 mm, natural frequency 360 Hz, corresponding to mid-frequency sound waves; Set 5, fork length 25 mm, thickness 1.5 mm, natural frequency 520 Hz, corresponding to high-frequency sound waves; Set 6, fork length 20 mm, thickness 1.5 mm, natural frequency 780 Hz, corresponding to high-frequency sound waves. The natural frequencies of the tuning fork structures 2 can be initially designed based on the approximate relationship of a cantilever beam and further corrected through finite element simulation.

[0021] In the formula: This represents the first-order approximate natural frequency of the sound wave signal corresponding to the prongs of the tuning fork; The effective length of the tuning fork strands, i.e., the length of the tuning fork structure 2, is represented by: E; the elastic modulus of the material of the tuning fork structure 2; I; the moment of inertia of the cross section of the tuning fork strands in the tuning fork structure 2; ρ; the material density of the tuning fork structure 2; and A; the cross-sectional area of ​​the tuning fork strands in the tuning fork structure 2. In addition, in this embodiment, the frequency response bandwidth of adjacent tuning fork groups is set to overlap at least partially to reduce the bandwidth gap caused by a single resonant peak.

[0022] The tuning fork structure 2 is mounted on the mounting base 3, which is suspended and fixed inside the receiving cavity by a pre-set support member; one end of each tuning fork structure 2 is fixed to the mounting base 3, and the other end of the tuning fork structure 2 is suspended inside the receiving cavity; the other end of the tuning fork structure 2 is provided with a triboelectric-piezoelectric hybrid structure. The triboelectric-piezoelectric hybrid structure includes a piezoelectric power generation unit 5 and a triboelectric power generation unit 4; the piezoelectric power generation unit 5 is disposed in the inner force-bearing region of the tuning fork structure 2; the triboelectric power generation unit 4 is disposed in the outer free end of the tuning fork structure 2; the triboelectric power generation unit 4 is used to output a triboelectric signal under the vibration condition of the sound wave signal input to the cavity; under the excitation of the sound wave signal input to the cavity, when the tuning fork structure 2 bends and deforms, the piezoelectric power generation unit generates polarized charge under the piezoelectric effect to output a piezoelectric signal; specifically, in this embodiment, multiple tuning fork structures 2 are disposed in the cavity Inside the cavity, at least some of the tuning fork structures 2 have different natural frequencies, i.e., different natural frequencies are formed by different fork strand sizes or material parameters; by placing the piezoelectric power generation unit 5 on the inner top side or the inner force-bearing area of ​​the tuning fork structure 2, it is used to convert alternating mechanical stress into piezoelectric signals when the tuning fork structure 2 vibrates under the excitation of sound waves; by placing the triboelectric power generation unit 4 on the outer top side or at the relative free end position of the tuning fork structures 2 arranged opposite to each other in the same group, it is used to form contact-separation motion and output triboelectric signals under the action of relative displacement generated by the vibration of the tuning fork structure 2. The power management circuit is used to acquire the acoustic energy of triboelectric and piezoelectric signals. In this embodiment, the power management circuit is electrically connected to the piezoelectric power generation unit 5 and the triboelectric power generation unit 4, respectively, and is used to perform rectification, filtering, and energy storage management operations on the piezoelectric and triboelectric signals, thereby converting broadband acoustic energy into electrical energy. Specifically, the power management circuit in this embodiment includes two rectifier branches, a filter capacitor, an energy storage capacitor, and a regulated output branch. The AC outputs of the piezoelectric power generation unit 5 and the triboelectric power generation unit 4 are rectified by independent rectifier branches and then connected in parallel to the energy storage capacitor. The rectifier branches can use Schottky diode full-bridge rectifier circuits, the filter capacitors can be 10μF ceramic capacitors, and the energy storage capacitors can be 100μF aluminum electrolytic capacitors. The regulated output branch can use an energy harvesting chip to provide a 3.3V regulated output.

[0023] In a specific embodiment, the piezoelectric power generation unit 5 includes a piezoelectric material layer 51 and a piezoelectric electrode 52; the bottom end face of the piezoelectric material layer 51 is connected to the top end face of the piezoelectric electrode 52; the top end face of the piezoelectric material layer 51 is provided with a flexible plate structure 53; and the bottom end face of the piezoelectric electrode 52 is provided with a flexible circuit connection plate 54.

[0024] Specifically, such as Figures 3 to 5As shown, the piezoelectric power generation unit 5 is arranged on the inner top side or the inner force-bearing area of ​​each tuning fork structure 2. The piezoelectric power generation unit 5 includes a piezoelectric material layer 51 and a piezoelectric electrode 52. The piezoelectric material layer 51 is made of piezoelectric ceramic and is formed on the inner top surface of the first and / or second tuning fork structures near the free end by screen printing. The piezoelectric material layer 51 has a length of 8 mm, a width of 5 mm, and a thickness of 50 μm. The piezoelectric electrode 5243 is made of silver and is deposited on the surface of the piezoelectric material layer 5142 by magnetron sputtering. The electrode thickness is 200 nm and is led out to the power management circuit through a copper wire with a diameter of 0.1 mm. The piezoelectric material layer 51 is any one or a combination of lead zirconate titanate piezoelectric ceramic, polyvinylidene fluoride piezoelectric film, and lead magnesium niobate-lead titanate piezoelectric single crystal.

[0025] In a specific embodiment, the triboelectric power generation unit 4 includes a first friction layer, a second friction layer, and friction electrodes respectively disposed corresponding to the first friction layer and the second friction layer; and the first friction layer and the second friction layer are formed of materials with different positions in the triboelectric sequence; the material combination of the first friction layer and the second friction layer is any one of polyester and polypropylene, polytetrafluoroethylene and nylon, and polytetrafluoroethylene and fluorinated ethylene propylene copolymer.

[0026] Specifically, such as Figure 3 and Figure 5 As shown, the triboelectric power generation unit 4 is arranged at the top outer free ends of each pair of opposing tuning fork structures 2. The triboelectric power generation unit 4 includes a first friction layer, a second friction layer, and a friction electrode. The first friction layer is coated with polyester (PET), and the second friction layer is coated with polypropylene (PP). Both the first and second friction layers have an area of ​​8 mm × 5 mm and a thickness of 100 μm. The first and second friction layers are respectively disposed on the top outer opposing surfaces of the two opposing tuning fork structures 2 in the same group and are electrically connected to the corresponding friction electrodes. When the tuning fork structures 2 in the same group vibrate relative to each other, the first and second friction layers periodically contact and separate, thereby generating triboelectric signals.

[0027] This embodiment aims to provide a triboelectric-piezoelectric hybrid tuning fork-shaped acoustic nanogenerator to alleviate the problems of narrow effective operating bandwidth, limited output from a single energy conversion mechanism, and insufficient structural integration in existing acoustic energy harvesting devices. Figure 6As shown, the working process of this embodiment is as follows: Sound wave signals of different frequencies enter the conical tapered cavity 1 through the sound wave inlet 11, and act on multiple tuning fork structures 2 under the guidance and reflection of the inner wall of the cavity; the multiple tuning fork structures 2 achieve frequency matching of the input sound waves through different natural frequencies, so that the corresponding tuning fork groups are driven and form a flexible response structure vibration. After the flexible response structure vibrates, on the one hand, the top outer triboelectric material layer generates relative vibration with the relative free ends, causing the first friction layer and the second friction layer to undergo periodic contact-separation motion, and outputting triboelectric signals under the action of triboelectric charging and electrostatic induction; on the other hand, the top inner piezoelectric material layer 51 deforms with the bending of the fork strands, and the piezoelectric material layer 51 generates polarized charges under the piezoelectric effect, and outputs piezoelectric signals through the piezoelectric electrode 52; the triboelectric signals and the piezoelectric signals are rectified, filtered and energy stored by the power management circuit, and finally achieve acoustic energy capture. In addition, from the perspective of energy conversion mechanism, both the triboelectric power generation unit 4 and the piezoelectric power generation unit 5 in this embodiment can be characterized by displacement current changes:

[0028] in: D represents displacement current density; E represents electric displacement vector; P represents electric field strength; P represents polarization vector. The vacuum dielectric constant is represented. For the triboelectric generator unit, the contact-separation motion causes the interfacial charge density to change with time, and a current is formed in the external circuit through electrostatic induction. For the piezoelectric generator unit 5, the cross-strand vibration causes the polarization state in the piezoelectric material layer 51 to change with stress, thereby forming a potential difference between the piezoelectric electrodes 52. Under the equivalent load model, the total output power of multiple piezoelectric generator units 5 and triboelectric generator units 4 can be expressed as: +

[0029] in: Indicates the total coupled output power; Indicates the first i The piezoelectric open-circuit equivalent voltage generated by mechanical stress on a sheet piezoelectric material; This represents the equivalent internal resistance of the piezoelectric element; This represents the voltage generated by the j-th triboelectric pair. This represents the equivalent internal resistance of the corresponding triboelectric unit; This refers to the piezoelectric induced voltage and the triboelectric voltage within the same composite coupling unit. This indicates the piezoelectric internal resistance and triboelectric internal resistance of the coupling unit. Geometric mean impedance representing piezoelectric and triboelectric internal resistance; This represents the piezoelectric-triboelectric coupling loss coefficient, which is determined by electromechanical coupling, electrostatic interference, and interface charge transfer, and 0 < 0. ≤1. This equivalent relationship is used to illustrate the output contribution of the two types of power generation units after being combined in the power management circuit, and does not constitute a limitation on the specific circuit topology or test conditions. Under laboratory test conditions, the sound source is a loudspeaker with a sound pressure level of 100-120 dB and a frequency range of 100-1000 Hz. The distance between the generator and the sound source is 0.5 m. Test results show that the coupled output of the twelve tuning fork structures 2 can cover an effective operating bandwidth of 120-850 Hz; under 120 dB and 260 Hz conditions, the maximum open-circuit voltage can reach 32 V, the maximum short-circuit current is 8.5 μA, and the maximum output power is 68 μW (load resistance 2 MΩ). The above performance data are results under specific prototype and test conditions, used to illustrate the effects of the embodiments, and do not limit the scope of protection of the present invention.

[0030] Example 2: This embodiment is basically the same as Embodiment 1, except that the piezoelectric material layer 51 is made of polyvinylidene fluoride (PVDF) piezoelectric film. The PVDF piezoelectric film has a thickness of 30 μm, a piezoelectric constant d33 of approximately -33 pC / N, and a relative permittivity of approximately 12. It is fixed to the inner top of the tuning fork structure 2 or the stress area inside the fork strands using epoxy resin adhesive. Due to the good flexibility of the PVDF piezoelectric film, it is suitable for... Figure 6 The diagram illustrates the piezoelectric deformation of the inner top surface of the flexible response structure after vibration. In this embodiment, the first and second friction layers in the triboelectric material layer are composed of polytetrafluoroethylene (PTFE) and nylon (PA-6); both the PTFE and PA-6 coatings are 80 μm thick and are respectively disposed on the outer top surfaces of the opposing free ends of the relative tuning fork structures 2 in the same group. This material combination exhibits significant differences in the triboelectric sequence, which is beneficial for improving... Figure 6 The amount of interfacial charge formed during the contact-separation process when the triboelectric element on the top outer side vibrates.

[0031] Example 3: This embodiment is basically the same as Embodiment 1, except that: the tuning fork structure 2 uses a variable cross-section fork; the width at the root of the fork is 8 mm, and the width at the free end of the fork is 4 mm, with the width gradually changing along the length of the fork. The variable cross-section design can improve stress concentration near the root of the fork, making... Figure 6 The piezoelectric unit 5 shown is or Figure 3 The piezoelectric material layer 51 exhibits a more uniform stress distribution. In this embodiment, the tapered cavity 1 employs a double-wall structure. The outer wall thickness is 2 mm, the inner wall thickness is 1 mm, and an air gap of 5 mm thickness is formed between the two layers. The air gap is used to adjust the acoustic impedance and reduce the interference of external structural vibrations on the tuning fork structure 2, thereby improving... Figure 1 and Figure 2The acoustic pressure coupling stability within the cavity is shown.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A triboelectric-piezoelectric hybrid tuning fork-shaped acoustic nanogenerator, characterized in that, It includes a tapered conical cavity (1) and a triboelectric-piezoelectric hybrid tuning fork acoustic structure; and the output of the tuning fork acoustic structure is connected to a power management circuit; The tapered converging cavity (1) is provided with a receiving cavity for converging sound waves; The tuning fork-shaped acoustic structure includes several tuning fork structures (2); Each of the tuning fork structures (2) is arranged at intervals along the cavity axis of the receiving cavity, and any two tuning fork structures (2) arranged opposite each other constitute a group of tuning fork structures; the tuning fork structures (2) between the groups of tuning fork structures have different lengths, so as to correspond to different sound frequencies of the sound wave signals input into the receiving cavity respectively; The tuning fork structure (2) is mounted on the mounting base (3), which is suspended and fixed inside the receiving cavity by a pre-set support member; and one end of each tuning fork structure (2) is fixed on the mounting base (3), while the other end of the tuning fork structure (2) is suspended inside the receiving cavity; the other end of the tuning fork structure (2) is provided with a triboelectric-piezoelectric hybrid structure. The triboelectric-piezoelectric hybrid structure includes a piezoelectric power generation unit (5) and a triboelectric power generation unit (4); the piezoelectric power generation unit (5) is located in the inner force-bearing area of ​​the tuning fork structure (2); the triboelectric power generation unit (4) is located at the outer free end of the tuning fork structure (2); the triboelectric power generation unit (4) is used to output a triboelectric signal under the vibration condition of the sound wave signal input to the cavity; under the excitation of the sound wave signal input to the cavity, when the tuning fork structure (2) is bent and deformed, the piezoelectric power generation unit generates polarized charge under the piezoelectric effect to output a piezoelectric signal; The power management circuit is used to acquire the acoustic energy of triboelectric and piezoelectric signals.

2. The triboelectric-piezoelectric hybrid tuning fork-shaped acoustic nanogenerator according to claim 1, characterized in that, The tuning fork structure (2) includes a first fork structure (21) and a second fork structure (22). One end of the first fork structure (21) and the second fork structure (22) are both located at the fixed point of the mounting base (3); and in any adjacent tuning fork structures (2), the first fork structure (21) of one tuning fork structure (2) and the second fork structure of the other tuning fork structure (2) are parallel to each other.

3. The triboelectric-piezoelectric hybrid tuning fork-shaped acoustic nanogenerator according to claim 2, characterized in that, The piezoelectric power generation unit (5) includes a piezoelectric material layer (51) and a piezoelectric electrode (52). The bottom surface of the piezoelectric material layer (51) is connected to the top surface of the piezoelectric electrode (52); the top surface of the piezoelectric material layer (51) is provided with a flexible plate structure (53); the bottom surface of the piezoelectric electrode (52) is provided with a flexible circuit connection plate (54).

4. The triboelectric-piezoelectric hybrid tuning fork-shaped acoustic nanogenerator according to claim 3, characterized in that, The piezoelectric material layer (51) is any one or a combination of lead zirconate titanate piezoelectric ceramic, polyvinylidene fluoride piezoelectric film, lead magnesium niobate-lead titanate piezoelectric single crystal.

5. The triboelectric-piezoelectric hybrid tuning fork-shaped acoustic nanogenerator according to claim 4, characterized in that, The triboelectric power generation unit (4) includes a first friction layer, a second friction layer, and friction electrodes respectively disposed corresponding to the first friction layer and the second friction layer; Furthermore, the first friction layer and the second friction layer are formed of materials with different triboelectric sequence positions.

6. The triboelectric-piezoelectric hybrid tuning fork acoustic nanogenerator according to claim 5, characterized in that, The material combination of the first friction layer and the second friction layer is any one of polyester and polypropylene, polytetrafluoroethylene and nylon, or polytetrafluoroethylene and fluorinated ethylene propylene copolymer.

7. A triboelectric-piezoelectric hybrid tuning fork-shaped acoustic nanogenerator according to claim 6, characterized in that, The tapered concave cavity (1) is provided with an acoustic inlet (11) and an acoustic outlet (12); and the cross-sectional area of ​​the acoustic inlet (11) is larger than the cross-sectional area of ​​the acoustic outlet (12); the inner wall of the tapered concave cavity (1) is also provided with an acoustic reflection layer for improving the acoustic pressure coupling efficiency.

8. The triboelectric-piezoelectric hybrid tuning fork acoustic nanogenerator according to claim 7, characterized in that, The formula for obtaining the length of the tuning fork structure (2) is as follows: In the formula: This represents the first-order approximate natural frequency of the sound wave signal corresponding to the prongs of the tuning fork; E represents the effective length of the tuning fork strand, i.e., the length of the tuning fork structure (2); E represents the elastic modulus of the material of the tuning fork structure (2); I represents the moment of inertia of the cross section of the tuning fork strand in the tuning fork structure (2); ρ represents the material density of the tuning fork structure (2); A represents the cross-sectional area of ​​the tuning fork strand in the tuning fork structure (2).

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