Multifunctional acoustic device with broadband sound insulation and acoustic-electric conversion

Abstract

The invention belongs to the technical field of acoustic functional materials and devices, and discloses a multifunctional acoustic device with broadband sound insulation and acoustic-electric conversion, which comprises a sound insulation unit, a support ring arranged on the front surface of the sound insulation unit, and a frictional electricity energy acquisition unit arranged on the support ring, the sound insulation unit comprises a multi-local-area resonance substrate, a polyimide film and a mass block assembly, the multi-local-area resonance substrate is divided into a center bending structure, a double-bending structure and a single-bending structure, the center bending structure drives a center mass block to vibrate in a reciprocating mode, so that the FEP film and the silica gel film are in periodic contact-separation, and the single-bending structure drives the center mass block to vibrate in a reciprocating mode; alternating current charge transfer is generated between the aluminum foil and the conducting layer, acoustic-electric conversion is achieved, and the three bending structures are coupled with the polyimide film and the mass block assembly. According to the invention, a plurality of effective sound insulation bands are formed in a low-frequency area based on the multi-local resonance structure and are used for inhibiting low-frequency sound propagation; and meanwhile, acoustic-electric energy conversion is realized by utilizing a triboelectric effect, and incident low-frequency acoustic energy is converted into electric energy.

Description

Technical Field

[0001] This application belongs to the field of acoustic functional materials and devices technology, specifically a multifunctional acoustic device with broadband sound insulation and sound-to-electric conversion. Background Technology

[0002] Noise control can typically be implemented from three aspects: the sound source, the propagation path, and the receiving end. Since noise generation is unavoidable in most engineering scenarios, and noise control at the source or receiving end is often limited by factors such as technology and cost, sound insulation by blocking the propagation path has become an important and feasible technical approach. Traditional sound insulation materials are constrained by the mass law; given their low surface density, they struggle to achieve sufficient sound insulation in the low-to-mid-frequency range of 20Hz-1000Hz, which contradicts the requirement for lightweight installations.

[0003] To overcome the bottleneck of low-frequency sound insulation, acoustic metamaterials have become a research hotspot. Existing research (Yang Z, Mei Jun, Yang Min, Chan NH, Sheng Ping. Membrane-type acoustic metamaterial with negative dynamic mass.[J]. Physical Review Letters, 2008, 101(20)) has proposed the concept of thin-film acoustic metamaterials, which utilize the equivalent negative dynamic mass effect to achieve sound insulation at low frequencies, providing a new approach to low-frequency sound insulation. However, such thin-film metamaterials often struggle to form wide sound insulation bands or multiple stable sound insulation peaks in the low-frequency range, resulting in limited sound insulation effects when dealing with low-frequency broadband noise.

[0004] To address the aforementioned issues, researchers have attempted to improve performance through structural modifications or coupling with other sound insulation mechanisms (Li, HZ; Liu, XC; Liu, Q.; Li, S.; Yang, JS; Tong, LL; Shi, SB; Schmidt, R.; Schroeder, K. Sound insulation performance of double membrane-type acoustic metamaterials combined with a Helmholtz resonator. Applied Acoustics 2023, 205.). However, this typically leads to an increase in device size and weight, diminishing the advantages of lightweight design.

[0005] Meanwhile, in thin-film acoustic metamaterials, the thin film, as an elastic element, needs to be subjected to tension. Tension has a significant impact on the resonant frequency, and uneven tension and stress relaxation can cause the sound insulation peak to drift, increasing the deviation between prediction and implementation.

[0006] To reduce the dependence on prestress, existing technologies (Ma, FY; Wu, JH; Huang, M. Resonant modalgroup theory of membrane-type acoustical metamaterials for low-frequency sound attenuation. European Physical Journal-Applied Physics 2015, 71) have proposed square lattice thin-film acoustic metamaterials that require almost no tension by increasing the film thickness, thus achieving the unification of thin-film and thin-plate acoustic metamaterials. However, research on multi-band sound insulation is still relatively insufficient.

[0007] On the other hand, low-frequency noise in the environment is essentially a form of usable mechanical energy. Concentrating acoustic energy and converting it into electrical energy holds promise for providing an energy source for low-power electronics and the zero-power Internet of Things (IoT). For example, existing technology (Zhang Qiqi, Xi Ziyue, Wang Yawei, Liu Ling, Yu Hongyong, Wang Hao, Xu Minyi. Multi-Tube Helmholtz Resonator Based Triboelectric Nanogenerator for Broadband Acoustic Energy Harvesting[J]. Frontiers in Materials, 2022) reports a triboelectric nanogenerator based on a multi-tube Helmholtz resonator for acoustic energy harvesting. However, this existing device only achieves the function of acoustic-electric energy conversion; its structural design does not involve multi-frequency sound insulation or structural-functional integration, resulting in insufficient space and resource utilization.

[0008] In summary, there is an urgent need for a lightweight, multi-local resonant acoustic device that is less sensitive to thin-film prestress. Summary of the Invention

[0009] To address the aforementioned technical problems, this application provides a multifunctional acoustic device with wideband sound insulation and acoustic-electric conversion. This multifunctional acoustic device constructs a substrate structure with multiple local resonances and integrates it with a contact-separation triboelectric energy harvesting unit. This multifunctional acoustic device can form multiple effective sound insulation bands in the low-frequency band to achieve multi-frequency sound insulation, while introducing triboelectric mechanism to achieve efficient acoustic-electric energy conversion, thereby improving functional integration and performance stability under the conditions of limited size and mass.

[0010] To achieve the above objectives, this application employs the following technical solution:

[0011] This application discloses a multifunctional acoustic device with broadband sound insulation and acoustic-electric conversion. The multifunctional acoustic device includes a sound insulation unit and a triboelectric energy harvesting unit. A support ring is set on the front of the sound insulation unit. The sound insulation unit includes a multi-local resonant substrate, a polyimide film, and a mass block assembly. The mass block assembly includes a central mass block and six circumferential mass blocks. The multi-local resonant substrate is divided into a central curved structure and several fan-shaped regions surrounding the outer periphery of the central curved structure. The fan-shaped regions are alternately arranged with double-curved structures and single-curved structures. The central curved structure, double-curved structures, and single-curved structures are coupled with the polyimide film and the mass block assembly. Through staggered local resonance, multiple effective sound insulation frequency bands are excited in the low-frequency range.

[0012] The triboelectric energy harvesting unit includes a silicone membrane and a triboelectric couple located at the center. The silicone membrane is tensioned and fixed on a support ring. The triboelectric couple includes a conductive layer uniformly coated on the back of the silicone membrane. The triboelectric couple also includes an aluminum foil and an FEP film sequentially arranged on a central mass block. The aluminum foil serves as the collector, the FEP film as the electronegative material, and the conductive layer as the electronegative electrode. When an external low-frequency sound pressure is applied to the multifunctional acoustic device, the central bending structure drives the central mass block to reciprocate, causing the FEP film and the silicone membrane to periodically contact and separate. An alternating current charge transfer is generated between the aluminum foil and the conductive layer. After rectification and energy storage circuitry, usable electrical energy is output, realizing sound-to-electric conversion.

[0013] A further improvement of this application is that the multi-local resonant substrate includes a circular outer frame, which is connected to a central ring by several crossbeams.

[0014] A further improvement of this application is that the central bending structure includes three equally spaced bending beams, one end of each equally spaced bending beam is connected to a central ring, and the other end of each equally spaced bending beam is connected to a central frustum, forming an elastic support for the vertical movement of the central frustum.

[0015] A further improvement of this application is that each double-bend structure includes two second-bend beams, one end of which is connected to the central ring and the other end to the small truncated cone, and the other end of which is connected to the small truncated cone and the other end to the circular outer frame.

[0016] A further improvement of this application is that each single-bend structure includes a first bending beam, one end of which is connected to a central ring, and the other end of which is connected to a small truncated cone.

[0017] A further improvement of this application is that: the outer dimensions of the central mass block are slightly smaller than those of the central frustum, the central mass block is bonded to the central frustum on the outside of the corresponding polyimide film, the circumferential mass blocks are matched with each small frustum, and the circumferential mass blocks are bonded to the small frustums on the outside of the corresponding polyimide film.

[0018] A further improvement of this application is that the outer diameter of the support ring is the same as that of the circular outer frame, and the thickness of the support ring is greater than that of the central mass block, serving as a limit and assembly step.

[0019] A further improvement of this application is that the polyimide film is cut according to the central frustum and the fan-shaped area in the central curved structure, the central frustum is covered with a film, the fan-shaped area is covered with a film, and an adhesive is applied to the same side surface of the circular frame, the crossbeam, the central ring, the central frustum and the small frustum to seal and bond the polyimide film to the multi-local resonance substrate, so as to form a local closed cavity and ensure airtightness.

[0020] The beneficial effects of this application are:

[0021] 1. This application addresses the problem of the single sound insulation frequency band of traditional thin-film acoustic metamaterials by innovatively using three different bending structures to form multiple local resonance modes. By utilizing the coupling of the local resonance structure with multiple bending structures and the silicone membrane, multiple effective sound insulation frequency bands are excited in the low-frequency range.

[0022] 2. Compared with traditional thin-film acoustic metamaterials, this application has more ways to control the sound insulation frequency band. It can take into account multiple dimensions such as the thickness and length of different curved structures, and the control method is efficient and applicable to different sound insulation scenarios.

[0023] 3. The application integrates acoustic-electric conversion with multi-frequency sound insulation devices, and innovatively covers the sound insulation unit with a silicone mold. It achieves efficient acoustic-electric conversion in the low-frequency range with almost no impact on sound insulation performance, and is a new type of multifunctional acoustic device.

[0024] 4. The polyimide film of this application has good mechanical and environmental resistance properties, the structure is easy to control and the installation can maintain good consistency with the finite element numerical simulation results. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of the multifunctional acoustic device of this application.

[0026] Figure 2 This is a schematic diagram of the sound insulation unit structure of the multifunctional acoustic device of this application.

[0027] Figure 3 This is a schematic diagram of the multi-local resonance substrate structure of the acoustic device of this application.

[0028] Figure 4 This is a flowchart of the finite element simulation analysis process.

[0029] Figure 5 This is a schematic diagram of the finite element simulation analysis model of this application.

[0030] Figure 6This is a schematic diagram comparing the sound insulation unit of this application with the sound insulation curve of the mass law.

[0031] Figure 7 This is a schematic diagram showing the sound pressure level distribution of the three sound insulation peaks and valleys of the sound insulation unit in this application.

[0032] Figure 8 STL curves showing only the central curved structure and the surrounding polyimide film.

[0033] Figure 9 STL curve diagram for replacing the bottom of the central curved structure with a solid PLA structure.

[0034] Figure 10 This is a schematic diagram illustrating the effect of silicone film on sound insulation performance.

[0035] Figure 11 This is a schematic diagram of the impedance tube sound insulation test system of this application.

[0036] Figure 12 This diagram shows a comparison of the experimental and simulation results of the impedance tube sound insulation of this structure.

[0037] Figure 13 This is a schematic diagram of the triboelectric nanogenerator performance testing system of this application.

[0038] Figure 14 This is a schematic diagram of the output voltage and current testing system of this application.

[0039] Figure 15 This is a physical image of the device in this application illuminating 12 LEDs connected in series under 100dB acoustic excitation.

[0040] Figure 16 This is a schematic diagram of the output voltage after acoustic-electric conversion obtained by testing under frequency-sweep acoustic excitation according to this application.

[0041] Figure 17 This is a schematic diagram of the output open-circuit voltage of the device under different sound pressure level excitations according to this application.

[0042] Figure 18 This is a schematic diagram of the short-circuit current output by the device under different sound pressure level excitations according to this application.

[0043] Figure 19 This is a schematic diagram of the voltage response waveform of this application under 150Hz sinusoidal excitation.

[0044] Figure 20 The voltage amplitude response of the triboelectric nanogenerator when air is gently blown onto the silicone membrane. Detailed Implementation

[0045] The embodiments of the present invention will be disclosed below with reference to the drawings. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details are not intended to limit the invention. That is, in some embodiments of the invention, these practical details are not essential.

[0046] like Figure 1 As shown, this application is a multifunctional acoustic device with broadband sound insulation and sound-to-electric conversion. The multifunctional acoustic device includes a sound insulation unit, and a support ring 140 is provided on the front of the sound insulation unit.

[0047] like Figure 2 As shown, the sound insulation unit includes a multi-local resonant substrate 110, a polyimide film 120, and a mass block assembly 130. The mass block assembly 130 includes a central mass block 131 and six circumferential mass blocks 132.

[0048] like Figure 3 As shown, the multi-local resonant substrate 110 includes a circular outer frame 111. The circular outer frame 111 is connected to a central ring 112 by several crossbeams 113, dividing the multi-local resonant substrate 110 into a central curved structure and six fan-shaped regions surrounding the outer periphery of the central curved structure. The six fan-shaped regions are alternately provided with double-curved structures and single-curved structures. The central curved structure, double-curved structures, and single-curved structures are coupled with a polyimide film 120 and a mass block assembly 130. Through staggered local resonance, multiple effective sound insulation frequency bands are excited in the low-frequency band.

[0049] The central bending structure includes three equally spaced bending beams 116c. One end of each equally spaced bending beam 116c is connected to a central ring 112, and the other end of each equally spaced bending beam 116c is connected to a central frustum 114, forming an elastic support for the vertical movement of the central frustum 114.

[0050] Each of the aforementioned double-bending structures includes two second bending beams 116b, one end of which is connected to the central ring 112 and the other end of which is connected to the small truncated cone 115, and the other end of which is connected to the small truncated cone 115 and the other end of which is connected to the circular outer frame 111.

[0051] Each of the single-bend structures includes a first bend beam 116a, one end of which is connected to the central ring 112, and the other end of which is connected to a small truncated cone 115.

[0052] The multi-local resonant substrate structure of this application uses three different bending structures with different equivalent stiffnesses in dynamics. By coupling them with a thin film and a mass block, substructures with different local resonant characteristics are formed, which obtains a variety of control methods, thereby forming staggered resonance in the low-frequency band to generate multiple sound insulation bands.

[0053] One part of the triboelectric energy harvesting unit consists of a conductive layer 230 located at the center of a silicone membrane 150. The silicone membrane 150 is tensioned and fixed to the support ring 140 to form a contact-separation action with the central mass block area and provide flexible rebound. The conductive layer 230 is preferably a multi-walled carbon nanotube (MWCNT) and has lead wires extending from it. The other part of the triboelectric harvesting unit includes an aluminum foil 210 and an FEP film 220 sequentially disposed on the central mass block 131. The aluminum foil 210 serves as an electrode and is led out through a lead wire. The FEP film 220 serves as an electronegative material. The conductive layer 230 serves as an electronegative material and an electrode. When external sound pressure is applied to the multifunctional acoustic device, the central bending structure drives the central mass block 131 to reciprocate, causing the FEP film 220 and the silicone membrane 150 to periodically contact and separate. An alternating current charge transfer is generated between the aluminum foil 210 and the conductive layer 230. After rectification and energy storage circuitry, usable electrical energy is output, realizing sound-to-electricity conversion. By integrating multi-frequency sound insulation bands and triboelectric energy harvesting within the same structure, sound insulation and power generation are achieved using the same acoustic vibration, thereby improving functional density and space utilization.

[0054] In this application, the silicone film 150 is mainly used as the carrier of the triboelectric nanogenerator, and its impact on the low-frequency sound insulation performance of the device is very small.

[0055] This application employs an independent film design, rather than using a single circular film covering structure. A circular film covers the central curved structure, while the surrounding six areas are covered with fan-shaped films. This reduces sensitivity to prestress, helps improve manufacturing consistency and long-term stability, and also facilitates subsequent maintenance and replacement.

[0056] The central mass block 131 is slightly smaller than the central frustum 114. After the polyimide film 120 is fixed on the multi-local resonance substrate 110, the central mass block 131 is bonded to the central frustum 114 on the outside of the corresponding polyimide film 120. The circumferential mass block 132 matches each of the small frustums 115. After the film 120 is cured, the circumferential mass block 132 is bonded to the small frustum 115 on the outside of the corresponding polyimide film 120. The position and centering of the mass block have a significant impact on the resonant frequency. It is preferable to use a positioning fixture to ensure bonding accuracy.

[0057] By changing the length L, thickness h, width w of the curved beam, the dimensions of the central frustum 114 and the small frustum 115, and the mass m of the central mass block 131 and the circumferential mass block 132, the elastic coefficient of each curved structure can be changed. The elastic coefficient will cause the resonant frequency to change, thereby controlling the sound insulation frequency band. Distributed sound insulation peaks can be formed between multiple units, and the multi-peak sound insulation band within the target low-frequency bandwidth can be designed. There are corresponding parameter coefficients for sound insulation treatment for different frequency band sound insulation scenarios.

[0058] The outer diameter of the support ring 140 is the same as that of the circular outer frame 111, and the thickness of the support ring 140 is preferably slightly larger than the thickness of the central mass block 131, so as to ensure that the triboelectric nanogenerator can achieve contact separation under acoustic excitation.

[0059] The polyimide film 120 is cut according to the central frustum 114 and the fan-shaped area in the central curved structure. The central frustum 114 is covered with a film, and the fan-shaped area is covered with a fan-shaped film. Adhesive is applied to the same side surfaces of the circular outer frame 111, crossbeam 113, central ring 112, central frustum 114, and small frustum 115 to seal and bond the polyimide film 120 to the multi-local resonant substrate 110, forming a local closed cavity and ensuring airtightness. The segmented coverage facilitates independent optimization and subsequent maintenance and replacement for different frequency band requirements. The central area uses a circular film, and the six sectors use fan-shaped films; the gaps between the films are sealed with adhesive, taking into account both sound insulation and maintainability.

[0060] The polyimide film in this application can be replaced with PI / TPU / PDMS, etc.; the silicone film can be replaced with other elastomers; FEP can be used in combination with PTFE / PDMS, etc.; the conductive layer can be made of metal-plated sheet, ITO or conductive fabric.

[0061] To study the low-frequency sound insulation performance of the designed multifunctional device, numerical analysis was performed using finite element simulation software, such as... Figure 4 This is a flowchart for calculating the sound insulation coefficient using finite element simulation.

[0062] The simulation model primarily utilizes two physical fields: pressure acoustics and solid mechanics. The solid mechanics domain corresponds to the multi-local resonant substrate structure, mass block, polyimide film, support ring, and silicone membrane, while the remaining areas are represented as air, corresponding to the pressure acoustics module.

[0063] The low-frequency sound insulation performance of this application was analyzed using finite element simulation, such as... Figure 5 As shown, the acoustic modules involved in the finite element model of this application include incident pressure field, hard sound field boundary wall, etc., and the sound wave radiation condition is plane wave radiation.

[0064] like Figure 6The schematic diagram of the sound insulation curve of the sound insulation unit obtained through simulation comparison analysis shows that in the frequency band of 20-1000Hz, there are sound insulation peaks at 340, 550 and 888Hz, and sound insulation valleys at 147, 440 and 691Hz. Figure 7 The sound pressure level distribution of the three peak and trough values ​​is shown. (See attached image) Figure 7 As shown, at the sound insulation peaks, the peak sound insulation values ​​all exceed 40dB, indicating that the sound insulation unit has excellent sound insulation capabilities, reflecting almost all incident sound waves. Compared to the sound insulation quality law curve, the sound insulation unit's sound insulation is superior to the sound insulation quality law curve in most frequency bands, only falling below the sound insulation quality law near the sound insulation trough. However, it should be noted that even at the sound insulation troughs (440, 691Hz), the sound insulation exceeds 15dB, demonstrating the sound insulation unit's good sound insulation capabilities over a wide frequency range.

[0065] This application further explores the impact of multi-local resonant substrate structures on sound insulation performance. Figure 8 This shows the STL (Sound Transmission Loss) curves for a structure retaining only the central curved structure and the surrounding polyimide film. The STL curve describes the attenuation of sound transmission by a material or structure within a specific frequency range; a higher loss indicates better sound isolation. This loss is typically measured in decibels (dB). Figure 8 As can be seen from the curves, since the central curved structure remains unchanged, the first sound insulation valley almost coincides with the STL curves of various curved structures. Furthermore, due to the absence of resonant frequencies from other curved structures, a second sound insulation peak is not generated in the low-frequency range. In addition, the amplitude of the first sound insulation peak is relatively low, and its bandwidth is also narrow. Figure 9 The bottom of the centrally curved structure was replaced with an STL curve of solid PLA. At this point, the structure has almost no sound insulation capability in the low-frequency range. Therefore, the centrally curved structure plays a crucial role in low-frequency sound insulation.

[0066] The finite element simulation also focused on exploring the impact of the silicone membrane on sound insulation performance, such as... Figure 10As shown, the STL curves illustrate three different configurations: a silicone diaphragm above the sound insulation unit, no silicone diaphragm, and a silicone diaphragm alone for sound insulation. It can be observed that when only the silicone diaphragm is used, its sound insulation performance is relatively weak across most frequency bands, with only one relatively significant sound insulation peak. When the silicone diaphragm is introduced, the initial peak of STL in the low-frequency range is essentially unaffected. However, a slight attenuation of the STL amplitude can be observed above 400Hz. Nevertheless, it still exhibits a relatively high level of sound insulation. Simultaneously, it can be seen that at 550Hz, the STL gradually decreases; conversely, at 579Hz, the STL increases rapidly, producing an additional sound insulation peak. This phenomenon is attributed to the inherent sound insulation peak characteristics of the silicone diaphragm itself. In summary, simulations confirm that the device of this application possesses satisfactory broadband sound insulation performance.

[0067] To verify that the multifunctional device proposed in this application can achieve good low-frequency multi-band sound insulation performance, experimental tests were conducted. The specific steps are as follows: The multifunctional device for experimental testing was printed using a 3D printer (Bamboo A1) with a multi-local resonant substrate and annular spacer, using Polylactic Acid (PLA) as the raw material. The polyimide film was pre-processed into seven pieces using a laser cutting machine. All parts were bonded together using 502 adhesive.

[0068] Reference Figure 1-3 , Figure 11-12 The multi-local resonant substrate designed in this application has an outer contour of a circle with a diameter of 100 mm. The outer contour of the central curved structure is 43 mm, and the diameter of its central frustum is 14 mm. The width of the three curved beams of the central curved structure is 2.5 mm, and the distance between them and the central frustum is 1.5 mm. The beam width of the single curved structure is 1 mm, and the distance between the beams is also 1 mm. The diameter of the frustum on which the mass block is placed is 10 mm. The beam width of both the single-curved and double-curved structures is 1 mm, and the distance between the beams is also 1 mm. The diameter of the frustum on which the mass block is placed is 10 mm. The biggest difference between the single-curved and double-curved structures lies in the length of the beams. The material properties of the multifunctional acoustic device are shown in Table 1.

[0069] Table 1

[0070]

[0071] To evaluate the sound insulation performance of the device in this application, a 100mm inner diameter impedance tube was used for sound insulation experiments, following the ASTM-2611-09 standard. A PXI-4461 acquisition card was used as a band-limited white noise signal source, and the excitation signal was amplified by a power amplifier to drive the speaker to excite the device. The experimental sample was located at the middle test position of the impedance tube, with the speaker positioned on one side of the tube. The other side of the impedance tube served as a sound-absorbing end, eliminating end reflection interference. Based on the sound insulation frequency band performance testing requirements, the frequency band tested for this impedance tube was 63-1000Hz. Four 1 / 4-inch microphones were used to collect the sound pressure before and after the sound waves reached the nanogenerator, and a PXI-4462 acquisition card was used to capture the sound pressure signal. The schematic diagram of the impedance tube sound insulation testing system is shown below. Figure 11 As shown in the figure. Its specific structure is shown in Table 2.

[0072] Table 2

[0073]

[0074] As shown in Table 2, a total of 2 sample devices were fabricated in the experiment, including 1 multifunctional device of this application; the comparison sample was a structure without silicone film.

[0075] Figure 12 The results of the impedance tube experimental tests and simulation tests are presented, including four types of experimental results: experimental test results and simulation test results of the device of this invention, and experimental test results and simulation test results of the comparative samples. The comparison between the impedance tube experimental test results and simulation test results shows that, regardless of the presence or absence of the silicone film, the experimental results are consistent with the FEM results, and the STL curve exhibits multiple effective sound insulation peaks and troughs. The maximum sound insulation of the sound insulation unit reaches 40dB, and the average sound insulation within 1000Hz reaches 26.18dB.

[0076] This application presents a multifunctional acoustic device that integrates a sound energy harvesting device and a multi-frequency sound insulation device, incorporates a contact-separated triboelectric nanogenerator to effectively achieve acoustic-electric conversion, and utilizes a local resonant structure design to achieve high-performance sound insulation in low-frequency multi-band with adjustable frequency band. This further confirms that the device can perform the reuse of low-frequency multi-band sound insulation and acoustic-electric conversion functions, making it a novel multifunctional acoustic device.

[0077] A schematic diagram of the structure of the triboelectric nanogenerator in this application is shown below. Figure 13As shown: The top layer is a silicone membrane. MWCNTs are evenly coated on the back of the silicone membrane. Aluminum foil and FEP are respectively attached to the central curved structure of the sound insulation unit. The sound insulation unit and the silicone membrane are connected by a support ring, which is placed on top of the multi-local resonant substrate structure. This creates a cavity between the silicone membrane and the polyimide film, allowing the silicone membrane and the central curved structure to move up and down. When the central curved structure moves up and down, it causes the electronegative membrane (FEP) fixed to the central mass block to come into contact with and separate from the elastic silicone membrane coated with conductive positively charged material (MWCNTs). A conductive current is formed between the electrodes of the positively charged and negatively charged materials. According to the principles of contact electrification and electrostatic induction, this reciprocating interaction generates alternating current between the electrodes, thus realizing the conversion of mechanical energy into electrical energy.

[0078] The sweep voltage, open-circuit voltage, short-circuit current, and load of the multifunctional acoustic device were measured. The voltage output of the nanogenerator was obtained using a PXI-4070 data acquisition card, with a 100x voltage attenuation probe used between the PXI-4070 and the nanogenerator to optimize input impedance and provide high-voltage protection. The short-circuit current was acquired using a PXI-4071 data acquisition card. The test results were displayed on a LabVIEW program on a PC. The performance of the acoustic-to-electric conversion was further verified using a circuit where a nanogenerator drives an LED array through a bridge rectifier. Figure 14 This is a schematic diagram of the output voltage and current testing system of the device in this application. Figure 15 This is a physical image of the device described in this application illuminating 12 LEDs connected in series under 100dB acoustic excitation.

[0079] First, a frequency sweep signal is output through a signal generator. Then, the frequency sweep voltage diagram in the LabVIEW program is shown below. Figure 16 The optimal power generation frequency of the generator was confirmed to be 150Hz. When the device was excited near the optimal frequency, the local resonance effect of the device was significant, and it had a large vibration energy. Combined with the contact-separated triboelectric nanogenerator, the vibration energy of the structure was converted into electrical energy, and the voltage response reached its peak.

[0080] Figure 17 and Figure 18 To measure the voltage and short-circuit current of a single device under sinusoidal acoustic wave excitation at different sound pressure levels, based on Figure 17 and Figure 18 The display shows that as the excitation increases, the output voltage and current also increase. Under a 100dB sound pressure level excitation, the peak-to-peak value of the output voltage is 75V and the peak-to-peak value of the output current is 0.77μA.

[0081] The voltage response waveform under 150Hz sinusoidal excitation is as follows: Figure 19As shown, the voltage waveform exhibits a near-perfect sine wave and periodic characteristics.

[0082] Figure 20 The experiment demonstrated that when air was gently blown onto the silicone membrane, the voltage response amplitude of the nanogenerator increased instantaneously, with a peak value of nearly 40V. This indicates that the device has high sensitivity to external acoustic signals.

[0083] This application proposes a multifunctional device for low-frequency broadband sound insulation and low-frequency acoustic energy to electrical energy conversion. Utilizing the characteristics of a local resonant structure, when the nanogenerator vibrates under noise excitation near the resonant frequency, it completes the reciprocating contact separation of the two electrified layers, generating electrical energy output and realizing low-frequency acoustic energy harvesting.

[0084] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A multifunctional acoustic device with broadband sound insulation and sound-to-electric conversion, characterized in that: The multifunctional acoustic device includes a sound insulation unit and a triboelectric energy harvesting unit, wherein a support ring (140) is provided on the front of the sound insulation unit, wherein: The sound insulation unit includes a multi-local resonant substrate (110), a polyimide film (120), and a mass block assembly (130); The mass block assembly (130) includes a central mass block (131) and six circumferential mass blocks (132); The multi-local resonant substrate (110) is divided into a central curved structure and several fan-shaped regions surrounding the outer periphery of the central curved structure. The fan-shaped regions are alternately provided with double-curved structures and single-curved structures. The central curved structure, double-curved structure and single-curved structure are coupled with a polyimide film (120) and a mass block assembly (130). Through staggered local resonance, multiple sound insulation frequency bands are excited in the low-frequency band. The triboelectric energy harvesting unit includes a silicone film (150) and a triboelectric couple located at the center. The silicone film (150) is tensioned and fixed on the support ring (140). The triboelectric couple includes a conductive layer (230) uniformly coated on the back of the silicone film (150). The triboelectric couple also includes an aluminum foil (210) and an FEP film (220) sequentially disposed on the central mass block (131). The aluminum foil (210) serves as a collector, the FEP film (220) serves as an electronegative material, and the conductive layer (230) serves as an electropositive electrode. When the external low-frequency sound pressure acts on the multifunctional acoustic device, the central bending structure drives the central mass block (131) to reciprocate, causing the FEP film (220) and the silicone film (150) to undergo periodic contact-separation. An alternating charge transfer is generated between the aluminum foil (210) and the conductive layer (230). The electrical energy is output through the rectification and energy storage circuit, realizing the sound-to-electric conversion.

2. The multifunctional acoustic device with broadband sound insulation and acoustic-electric conversion as described in claim 1, characterized in that: The multi-local resonant substrate (110) includes a circular outer frame (111), which is connected to a central ring (112) by a plurality of crossbeams (113).

3. The multifunctional acoustic device with broadband sound insulation and acoustic-electric conversion as described in claim 2, characterized in that: The central bending structure includes three equally spaced bending beams (116c), one end of each equally spaced bending beam (116c) is connected to a central ring (112), and the other end of each equally spaced bending beam (116c) is connected to a central frustum (114), forming an elastic support for the vertical movement of the central frustum (114).

4. A multifunctional acoustic device with broadband sound insulation and acoustic-electric conversion as described in claim 2, characterized in that: Each of the aforementioned double-bending structures includes two second-bending beams (116b), one end of which is connected to the central ring (112) and the other end of which is connected to the small truncated cone (115), and the other end of which is connected to the small truncated cone (115) and the other end of which is connected to the circular outer frame (111).

5. A multifunctional acoustic device with broadband sound insulation and acoustic-electric conversion as described in claim 2, characterized in that: Each of the single-bend structures includes a first bend beam (116a), one end of which is connected to the central ring (112), and the other end of which is connected to a small truncated cone (115).

6. The multifunctional acoustic device with broadband sound insulation and acoustic-electric conversion as described in claim 1, characterized in that: The outer dimensions of the central mass block (131) are smaller than those of the central frustum (114). The central mass block (131) is bonded to the central frustum (114) on the outside of the corresponding polyimide film (120). The circumferential mass block (132) matches each of the small frustums (115). The circumferential mass block (132) is bonded to the small frustums (115) on the outside of the corresponding polyimide film (120).

7. A multifunctional acoustic device with broadband sound insulation and acoustic-electric conversion as described in claim 1, characterized in that: The outer diameter of the support ring (140) is the same as that of the circular outer frame (111), and the thickness of the support ring (140) is greater than that of the central mass block (131), serving as a limiting and assembly step.

8. A multifunctional acoustic device with broadband sound insulation and sound-to-electric conversion as described in claim 1, characterized in that: The polyimide film (120) is cut according to the central frustum (114) and the fan-shaped area in the central curved structure. The central frustum (114) is covered with a film, and the fan-shaped area is covered with a film. Adhesive is applied to the same side surface of the circular outer frame (111), the crossbeam (113), the central ring (112), the central frustum (114) and the small frustum (115) to seal and bond the polyimide film (120) to the multi-local resonance substrate (110) to form a local closed cavity and ensure airtightness.

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