A broadband acoustic signal amplifier based on nested space-fold metamaterials

Abstract

The application provides a broadband sound signal amplifier based on nested space folding metamaterials, and belongs to the field of sound signal amplifying devices in the acoustic information technology and acoustics sensing field. How to develop a metamaterial sound signal amplifier with significant sound field enhancement capability, wide working bandwidth and compact structure is solved. The acoustic amplifier is a composite metamaterial structure composed of two groups of nested space folding structures, including an inner layer space step folding structure and an outer layer space gradient gradual folding structure. After the sound wave is incident through the outer layer folding structure, the sound wave continues to propagate in the inner layer folding structure, and the sound field coupling of the inner layer and the outer layer folding structure is realized through the size design of the inner layer and the outer layer structure, so that the sound signal amplification frequency band can be effectively widened. The application effectively widens the working bandwidth of the sound signal amplifier based on the space folding metamaterials without increasing the size of the device, and provides a new idea and technology for developing sound wave or mechanical wave amplifiers.

Description

Technical Field

[0001] This invention belongs to the field of acoustic signal amplification devices in the fields of acoustic information technology and sensing, and in particular relates to a broadband acoustic signal amplifier based on nested spatial folded metamaterials. Background Technology

[0002] Acoustic amplifiers are core components in the fields of acoustic signal processing and sensing, and have wide applications in acoustic information technology and sensing. For example, high-performance acoustic amplifiers are required in many fields such as underwater acoustic navigation and communication, structural health monitoring and fault diagnosis, voice recognition systems, and human-computer interaction intelligent terminals. In recent years, significant progress has been made in the development of new acoustic amplifiers, but their performance and functional limitations still restrict the development of acoustic information technology and equipment. For instance, acoustic sensors are not sensitive enough to detect extremely weak signals, and sonar has limited detection range. Therefore, further research and development of new acoustic amplifiers is still needed to improve the performance of acoustic detection equipment.

[0003] Acoustic metamaterials are a class of artificial composite materials that have emerged in recent years, formed by arranging subwavelength structures in a periodic or aperiodic manner. They can flexibly manipulate sound waves in fluids and solids to achieve unique acoustic phenomena. Studies have shown that gradient acoustic metamaterials can achieve sound wave compression and sound field amplification, thereby improving the detection capability of weak sound signals. However, most gradient acoustic metamaterials usually require a large length and size to overcome the sound propagation loss caused by the discontinuity of the material structure. The devices are large in size, expensive to manufacture, and inconvenient for portability and practical applications.

[0004] Space-folded metamaterials extend the sound wave propagation path through their folded structures, achieving sound energy concentration and signal amplification based on the resulting acoustic resonance. This makes them suitable for weak signal detection and acoustic sensing. However, traditional space-folded metamaterials often contain unutilized cavities, resulting in insufficient gain in the low-frequency range, or a narrow bandwidth for significant sound field gain, typically only tens of Hz, which fails to meet current industrial needs.

[0005] Based on the above technical challenges, there is an urgent need to develop a metamaterial acoustic signal amplifier with significant sound field enhancement capabilities, a wide operating bandwidth, and a compact structure. This would significantly reduce the difficulty and cost of device fabrication. The miniaturized, high-gain broadband acoustic signal amplifier is expected to be widely used in industrial acoustic detection, acoustic probing, and communication. Summary of the Invention

[0006] In view of this, in order to solve the technical problems mentioned in the background art, the present invention proposes a broadband acoustic signal amplifier based on nested spatial folded metamaterials. Through the development of the present invention, the structural size of the metamaterial acoustic amplifier is significantly reduced, the operating bandwidth with significant sound field gain is significantly increased, and it has good prospects for engineering applications.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a broadband acoustic signal amplifier based on nested spatial folded metamaterials, comprising an inner folded structure and an outer folded structure. Both the inner and outer folded structures are composed of multiple layers of alternating arc-shaped partitions. The inner and outer folded structures are coaxially arranged and located within the central cavity of the outer folded structure. The inner folded structure adopts a step folded structure, and the outer folded structure adopts a gradient folded structure. After the sound wave is incident on the outer folded structure, it continues to propagate in the inner folded structure, thereby amplifying the acoustic signal at a specific frequency.

[0008] Preferably, the inner folded structure has four folded layers, with acoustic channel widths g1n=g2n=g3n=gn, g4n=gn+dgn, where gn is the initial channel width of the inner fold, and dgn is the step parameter of the inner fold. The arc-shaped partitions that make up the inner and outer folded structures have the same height, h, which is adjusted within the range of 10mm-100mm according to the actual acoustic signal amplification requirements and experimental equipment limitations. The inner and outer folded structures are made of rigid plastic 3D printing or stainless steel or aluminum alloy.

[0009] Preferably, the outer folded structure has a 4-layer gradient folded structure, with acoustic channel widths g1=g+dg×3, g2=g+dg×2, g3=g+dg, and g4=g, where g is the initial channel width of the outer fold and dg is the gradient change parameter of the outer fold.

[0010] Preferably, when the amplifier's operating frequency range is 384Hz-720Hz, the inner layer folded structure has the following acoustic channel widths: g1n=g2n=g3n=1mm, g4n=4mm, gn=1mm, dgn=3mm, opening width wn=0.75mm, central cavity radius r1n=4mm, arc-shaped partition thickness tn=0.5mm, and number of partitions Mn=3. The outer layer folded structure has the following acoustic channel widths: g1=19mm, g2=13mm, g3=7mm, g4=1mm, g=1mm, dg=6mm, opening width w=1.5mm, central cavity radius R1=15mm, arc-shaped partition thickness t=1mm, and number of partitions M=6. The height of the arc-shaped partitions forming the inner and outer folded structures is h=20mm.

[0011] Preferably, when the amplifier's operating frequency range is 193Hz-366Hz, the inner layer folded structure has the following acoustic channel widths: g1n=g2n=g3n=2mm, g4n=8mm, gn=2mm, dgn=6mm, opening width wn=1.5mm, central cavity radius r1n=8mm, arc-shaped partition thickness tn=1mm, and number of partitions Mn=3. The outer layer folded structure has the following acoustic channel widths: g1=38mm, g2=26mm, g3=14mm, g4=2mm, g=2mm, dg=12mm, opening width w=3mm, central cavity radius R1=30mm, arc-shaped partition thickness t=2mm, and number of partitions M=6. The height of the arc-shaped partitions that make up the inner and outer folded structures is h=10mm.

[0012] Preferably, when the amplifier's operating frequency range is 257Hz-485Hz, the inner layer folded structure has the following acoustic channel widths: g1n=g2n=g3n=1.5mm, g4n=6mm, gn=1.5mm, dgn=4.5mm, opening width wn=1.125mm, central cavity radius r1n=6mm, arc-shaped partition thickness tn=0.75mm, and number of partitions Mn=3. The outer layer folded structure has the following acoustic channel widths: g1=28.5mm, g2=19.5mm, g3=10.5mm, g4=1.5mm, g=1.5mm, dg=9mm, opening width w=2.25mm, central cavity radius R1=22.5mm, arc-shaped partition thickness t=1.5mm, and number of partitions M=6. The height of the arc-shaped partitions forming the inner and outer folded structures is h=15mm.

[0013] Preferably, the outer folded structure has a 5-layer gradient folded structure, with the acoustic channel widths g1=g+dg×4, g2=g+dg×3, g3=g+dg×2, g4=g+dg, and g5=g, where g is the initial channel width of the outer fold and dg is the gradient change parameter of the outer fold.

[0014] Preferably, when the amplifier's operating frequency range is 507Hz-727Hz, the inner layer folded structure has the following acoustic channel widths: g1n=g2n=g3n=1mm, g4n=4mm, gn=1mm, dgn=3mm, opening width wn=0.75mm, central cavity radius r1n=4mm, arc-shaped partition thickness tn=0.5mm, and number of partitions Mn=3. The outer layer folded structure has the following acoustic channel widths: g1=29mm, g2=23mm, g3=17mm, g4=11mm, g5=5mm, g=5mm, dg=6mm, opening width w=1.5mm, central cavity radius R1=15mm, arc-shaped partition thickness t=1mm, and number of partitions M=6. The height of the arc-shaped partitions forming the inner and outer folded structures is h=18mm.

[0015] Preferably, when the amplifier's operating frequency range is 254Hz-367Hz, the inner layer folded structure has the following acoustic channel widths: g1n=g2n=g3n=2mm, g4n=8mm, gn=2mm, dgn=6mm, opening width wn=1.5mm, central cavity radius r1n=8mm, arc-shaped partition thickness tn=1mm, and number of partitions Mn=3. The outer layer folded structure has the following acoustic channel widths: g1=58mm, g2=46mm, g3=34mm, g4=22mm, g5=10mm, g=10mm, dg=12mm, opening width w=3mm, central cavity radius R1=30mm, arc-shaped partition thickness t=2mm, and number of partitions M=6. The height of the arc-shaped partitions forming the inner and outer folded structures is h=23mm.

[0016] Preferably, when the amplifier's operating frequency range is 339Hz-488Hz, the inner layer folded structure has the following acoustic channel widths: g1n=g2n=g3n=1.5mm, g4n=6mm, gn=1.5mm, dgn=4.5mm, opening width wn=1.125mm, central cavity radius r1n=6mm, arc-shaped partition thickness tn=0.75mm, and number of partitions Mn=3. The outer layer folded structure has the following acoustic channel widths: g1=43.5mm, g2=34.5mm, g3=25.5mm, g4=16.5mm, g5=7.5mm, g=7.5mm, dg=9mm, opening width w=2.25mm, central cavity radius R1=22.5mm, arc-shaped partition thickness t=1.5mm, and number of partitions M=6. The height of the arc-shaped partitions forming the inner and outer folded structures is h=28mm.

[0017] Compared with existing technologies, the advantages of the broadband acoustic signal amplifier based on nested spatially folded metamaterials described in this invention are: (1) After the sound wave passes through the outer gradient folded structure, it will continue to propagate in the inner step folded structure and eventually reach the central cavity. The refractive index of the outer gradient folded structure is significantly different from that of the inner step folded structure, which causes the sound field to couple after the two structures are nested. That is, the resonant peaks corresponding to the inner step structure and the outer gradient folded structure are superimposed, thereby widening the effective working bandwidth and making it more suitable for practical applications. Compared with existing gradient acoustic metamaterials, the nested spatial folded metamaterial amplifier is smaller in size, has a higher degree of freedom in adjustable parameters, and has a wider low-frequency working bandwidth. At present, acoustic amplifiers based on folded structures can only adapt to different frequencies by changing structural parameters or scaling the overall geometric size. It is difficult to achieve a tenfold sound field amplification with a bandwidth of more than 100Hz in the low frequency. However, the nested folded structure with inner step and outer gradient can achieve low-frequency wideband operation without secondary design of structural parameters or scaling of the structure.

[0018] (2) The present invention embeds the inner step folding structure into the central cavity of the outer gradient folding structure. Without increasing the volume and size of the acoustic signal amplifier, broadband acoustic signal amplification can be achieved by adjusting the structural parameters of the inner and outer layers of the nested spatial folding structure, effectively broadening the working frequency band with significant sound field gain.

[0019] (3) The inner and outer folded structures can be flexibly designed and matched according to the actual experimental equipment requirements, and are not limited to the initial design size and matching method. Different designs of outer gradient folded structures can be matched with the same inner step structure, or different designs of inner step structures can be matched with the same outer gradient folded structure to achieve effective control of the working frequency band. For application scenarios that require flexible control of the working frequency band, it can save design time and processing costs and has great application potential.

[0020] (4) Based on the above-mentioned features of the present invention, the proposed broadband acoustic signal amplifier based on nested spatial folded metamaterials can be applied to fields such as robotic sonar detection systems, structural health monitoring and fault diagnosis, and medical detection instruments. Similar design principles can be used for elastic wave metamaterials to improve the problems of large size, narrow bandwidth, and difficulty in practical application of traditional metamaterial functional devices. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of a nested spatial folding structure, where 1 is the inner folding structure and 2 is the outer folding structure. Figure 2 The diagram shows a top view of a nested spatial folding structure, where (a) is a top view of the structure of Embodiment 1, with an inner layer of 4-layer step folding structure and an outer layer of 4-layer gradient folding structure; (b) is a top view of the structure of Embodiment 2, with an inner layer of 4-layer step folding structure and an outer layer of 5-layer gradient folding structure. Figure 3 The sound field pressure distribution diagrams are shown for the nested spatial folded metamaterial structures, where (a) is the sound field pressure distribution diagram of Example 1 at a resonant frequency of 475 Hz, (b) is the sound field pressure distribution diagram of Example 1 at a resonant frequency of 630 Hz, (c) is the sound field pressure distribution diagram of Example 2 at a resonant frequency of 570 Hz, and (d) is the sound field pressure distribution diagram of Example 2 at a resonant frequency of 680 Hz. Figure 4 The pressure frequency response diagrams are for the acoustic signal amplifier of the nested spatial folded metamaterial, where (a) is the pressure frequency response diagram of Example 1 and (b) is the pressure frequency response diagram of Example 2. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the drawings, and not all of them. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the invention.

[0023] Example 1 See Figure 1-4 This embodiment describes a broadband acoustic signal amplifier based on nested spatially folded metamaterials, comprising an inner folded structure 1 and an outer folded structure 2. Both the inner folded structure 1 and the outer folded structure 2 are composed of multiple layers of alternating arc-shaped partitions. The inner folded structure 1 and the outer folded structure 2 are coaxially arranged and located within the central cavity of the outer folded structure 2. The inner folded structure 1 adopts a step-folded structure, while the outer folded structure 2 adopts a gradient-change folded structure. After sound waves are incident on the outer folded structure, they continue to propagate in the inner folded structure 1, amplifying acoustic signals at specific frequencies. Through the design of the spatial configuration and structural dimensions of the inner and outer folded structures, the acoustic signal amplification bandwidth can be effectively broadened.

[0024] Detailed structure of nested spatial folded metamaterials, such as Figure 2 As shown, where Figure 2 (a) shows the detailed structure of Example 1. The inner folded structure 1 has four folded structures with acoustic channel widths g1n=g2n=g3n=gn, g4n=gn+dgn, where gn is the initial channel width of the inner fold, dgn is the step parameter of the inner fold, the inner fold structure has Mn partitions, an opening width wn, a central cavity radius r1n, and an arc-shaped partition thickness tn. The outer folded structure 2 has four gradient folded structures with acoustic channel widths g1=g+dg×3, g2=g+dg×2, g3=g+dg, g4=g, where g is the initial channel width of the outer fold, dg is the gradient parameter of the outer fold, the outer fold structure 2 has M partitions, an opening width w, a central cavity radius R1, and an arc-shaped partition thickness t. The arc-shaped partitions that make up the inner folded structure 1 and the outer folded structure 2 have the same height, h. The height h of the inner and outer folded arc-shaped partition can be flexibly adjusted within the range of 10mm-100mm according to the actual sound signal amplification requirements and the limitations of experimental equipment.

[0025] The amplifier operates in the frequency range of 384Hz-720Hz. The inner folded structure 1 has the following acoustic channel widths: g1n=g2n=g3n=1mm, g4n=4mm, gn=1mm, dgn=3mm, opening width wn=0.75mm, central cavity radius r1n=4mm, arc-shaped partition thickness tn=0.5mm, and number of partitions Mn=3. The outer folded structure 2 has the following acoustic channel widths: g1=19mm, g2=13mm, g3=7mm, g4=1mm, g=1mm, dg=6mm, opening width w=1.5mm, central cavity radius R1=15mm, arc-shaped partition thickness t=1mm, and number of partitions M=6. The height h of the arc-shaped partitions forming the inner and outer folded structures 1 and 2 is 20mm.

[0026] The amplifier operates within a frequency range of 193Hz-366Hz. The inner folded structure 1 has the following acoustic channel widths: g1n=g2n=g3n=2mm, g4n=8mm, gn=2mm, dgn=6mm, opening width wn=1.5mm, central cavity radius r1n=8mm, arc-shaped partition thickness tn=1mm, and number of partitions Mn=3. The outer folded structure 2 has the following acoustic channel widths: g1=38mm, g2=26mm, g3=14mm, g4=2mm, g=2mm, dg=12mm, opening width w=3mm, central cavity radius R1=30mm, arc-shaped partition thickness t=2mm, and number of partitions M=6. The height h of the arc-shaped partitions forming the inner and outer folded structures 1 and 2 is 10mm.

[0027] The amplifier operates in the frequency range of 257Hz-485Hz. The inner folded structure 1 has the following acoustic channel widths: g1n=g2n=g3n=1.5mm, g4n=6mm, gn=1.5mm, dgn=4.5mm, opening width wn=1.125mm, central cavity radius r1n=6mm, arc-shaped partition thickness tn=0.75mm, and number of partitions Mn=3. The outer folded structure 2 has the following acoustic channel widths: g1=28.5mm, g2=19.5mm, g3=10.5mm, g4=1.5mm, g=1.5mm, dg=9mm, opening width w=2.25mm, central cavity radius R1=22.5mm, arc-shaped partition thickness t=1.5mm, and number of partitions M=6. The height h of the arc-shaped partitions forming the inner and outer folded structures 1 and 2 is 15mm.

[0028] Example 2: See Figure 1-4This embodiment describes a broadband acoustic signal amplifier based on nested spatial folded metamaterials, comprising an inner folded structure 1 and an outer folded structure 2. Both the inner folded structure 1 and the outer folded structure 2 are composed of multiple layers of alternating arc-shaped partitions. The inner folded structure 1 and the outer folded structure 2 are coaxially arranged and located within the central cavity of the outer folded structure 2. The inner folded structure 1 adopts a step folded structure, while the outer folded structure 2 adopts a gradient folded structure. After the sound wave is incident on the outer folded structure 2, it continues to propagate in the inner folded structure 1, thereby amplifying the acoustic signal at a specific frequency.

[0029] Detailed structure of nested spatial folded metamaterials, such as Figure 2 As shown, where Figure 2 (b) shows the detailed structure of Example 2. The inner folded structure 1 has 4 folded structures with acoustic channel widths g1n=g2n=g3n=gn, g4n=gn+dgn, where gn is the initial channel width of the inner fold and dgn is the step parameter of the inner fold. The outer folded structure 2 has 5 gradient folded structures with acoustic channel widths g1=g+dg×4, g2=g+dg×3, g3=g+dg×2, g4=g+dg, g5=g, where g is the initial channel width of the outer fold and dg is the gradient parameter of the outer fold. The outer folded structure 2 has M partitions, an opening width w, a central cavity radius R1, and an arc-shaped partition thickness t. The arc-shaped partitions that make up the inner folded structure 1 and the outer folded structure 2 have the same height, h. The height h of the arc-shaped partitions of the inner and outer folded structures can be flexibly adjusted within the range of 10mm-100mm according to the actual acoustic signal amplification requirements and experimental equipment limitations.

[0030] The amplifier operates in the frequency range of 507Hz-727Hz. The inner folded structure 1 has the following acoustic channel widths: g1n=g2n=g3n=1mm, g4n=4mm, gn=1mm, dgn=3mm, opening width wn=0.75mm, central cavity radius r1n=4mm, arc-shaped partition thickness tn=0.5mm, and number of partitions Mn=3. The outer folded structure 2 has the following acoustic channel widths: g1=29mm, g2=23mm, g3=17mm, g4=11mm, g5=5mm, g=5mm, dg=6mm, opening width w=1.5mm, central cavity radius R1=15mm, arc-shaped partition thickness t=1mm, and number of partitions M=6. The height h of the arc-shaped partitions forming the inner and outer folded structures 1 and 2 is 18mm.

[0031] The amplifier operates in the frequency range of 254Hz-367Hz. The inner folded structure 1 has the following acoustic channel widths: g1n=g2n=g3n=2mm, g4n=8mm, gn=2mm, dgn=6mm, opening width wn=1.5mm, central cavity radius r1n=8mm, arc-shaped partition thickness tn=1mm, and number of partitions Mn=3. The outer folded structure 2 has the following acoustic channel widths: g1=58mm, g2=46mm, g3=34mm, g4=22mm, g5=10mm, g=10mm, dg=12mm, opening width w=3mm, central cavity radius R1=30mm, arc-shaped partition thickness t=2mm, and number of partitions M=6. The height h of the arc-shaped partition forming the inner and outer folded structures 1 and 2 is 23mm.

[0032] The amplifier operates in the frequency range of 339Hz-488Hz. The inner folded structure 1 has the following acoustic channel widths: g1n=g2n=g3n=1.5mm, g4n=6mm, gn=1.5mm, dgn=4.5mm, opening width wn=1.125mm, central cavity radius r1n=6mm, arc-shaped partition thickness tn=0.75mm, and number of partitions Mn=3. The outer folded structure 2 has the following acoustic channel widths: g1=43.5mm, g2=34.5mm, g3=25.5mm, g4=16.5mm, g5=7.5mm, g=7.5mm, dg=9mm, opening width w=2.25mm, central cavity radius R1=22.5mm, arc-shaped partition thickness t=1.5mm, and number of partitions M=6. The height h of the arc-shaped partitions forming the inner and outer folded structures 1 and 2 is 28mm.

[0033] The same technology as in Examples 1 and 2 also includes: the inner and outer folded structures are made by 3D printing of rigid plastics (such as photosensitive resin) or by processing metals such as stainless steel and aluminum alloys. Rigid plastic sheets are mainly used for testing in air, while metal sheets are mainly used for detecting, receiving, and communicating weak signals in underwater environments.

[0034] The manufacturing method of the broadband acoustic signal amplifier based on nested spatial folded metamaterials is as follows: using 3D printing technology, an acoustic signal amplifier with supporting planes on the top and bottom can be obtained.

[0035] The design of this invention is not limited to the two designs in Embodiment 1 and Embodiment 2. Other equivalent designs can be implemented by increasing the number of nested structures, expanding the number of layers or the thickness of the design structure, etc. The two embodiments are listed to demonstrate the ability of nested structures to broaden the operating frequency band.

[0036] Figure 3The figures show the sound field pressure distribution at the resonant frequency for Embodiments 1 and 2 of the present invention, where (a) and (b) are the sound field pressure distribution at the resonant frequency for Embodiment 1; and (c) and (d) are the sound field pressure distribution at the resonant frequency for Embodiment 2. As can be seen from the figures, the sound pressure value of the inner folded structure 1 is significantly higher than that of the outer folded structure 2. This is because when sound waves are incident on the nested spatial folded metamaterial, they first pass through the outer folded structure 2 before entering the inner folded structure 1, further extending the sound wave transmission distance and propagation time. This concentrates the sound waves within a specific range, amplifying the sound signal and resulting in a significant sound field gain, thereby enabling better detection and reception of weak signals.

[0037] Figure 4 The diagrams show the sound pressure gain frequency response of Embodiments 1-2 of this invention. Sound pressure gain refers to the ratio of the sound pressure amplitude when a sound wave propagates within a metamaterial structure to the sound pressure amplitude when the sound wave propagates freely in the air without a metamaterial structure. (a) shows the frequency response of the metamaterial amplifier in Embodiment 1 within the range of 10 Hz to 1000 Hz, with a sound pressure gain of 15.6 times at a resonant frequency of 475 Hz and 12.6 times at 630 Hz. Within the range of 384 Hz to 720 Hz, a sound field gain exceeding 5 times can be achieved, with a bandwidth of 336 Hz. Within the range of 432 Hz to 665 Hz, a sound field gain exceeding 10 times can be achieved, with a bandwidth of 233 Hz. (b) shows the frequency response of the metamaterial amplifier in Embodiment 2 within the range of 400 Hz to 900 Hz, with a sound pressure gain of 17.4 times at a resonant frequency of 570 Hz and 13.85 times at 680 Hz. Within the 507 Hz-727 Hz range, a sound field gain of over 5 times can be achieved with a bandwidth of 220 Hz. Within the 542 Hz-698 Hz range, a sound field gain of over 10 times can be achieved with a bandwidth of 156 Hz. Nested spatially folded metamaterials not only achieve significant acoustic signal amplification at resonant frequencies, but also simultaneously achieve broadband acoustic signal amplification and gain of over 5 times and 10 times, making them suitable for applications requiring weak signal reception and detection.

[0038] The embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A broadband acoustic signal amplifier based on nested spatially folded metamaterials, characterized in that: It includes an inner folded structure (1) and an outer folded structure (2). Both the inner folded structure (1) and the outer folded structure (2) are composed of multiple layers of arc-shaped partitions arranged alternately. The inner folded structure (1) and the outer folded structure (2) are coaxially arranged and located in the central cavity of the outer folded structure (2). The inner folded structure (1) adopts a step folded structure, and the outer folded structure (2) adopts a gradient folded structure. After the sound wave passes through the outer folded structure (2), it continues to propagate in the inner folded structure (1), thereby amplifying the broadband sound signal. The inner folded structure (1) has a 4-layer folded structure with a sound channel width of g1n=g2n=g3n=gn, g4n=gn+dgn, where gn is the initial channel width of the inner fold and dgn is the step parameter of the inner fold.

2. The broadband acoustic signal amplifier based on nested spatially folded metamaterials according to claim 1, characterized in that: The arc-shaped partitions that make up the inner folded structure (1) and the outer folded structure (2) have the same height, which is h. The height is adjusted within the range of 10mm-100mm according to the actual sound signal amplification requirements and the limitations of the experimental equipment. The inner folded structure (1) and the outer folded structure (2) are made of hard plastic 3D printing or stainless steel or aluminum alloy.

3. The broadband acoustic signal amplifier based on nested spatially folded metamaterials according to claim 2, characterized in that: The outer folded structure (2) has a 4-layer gradient folded structure with a sound channel width of g1=g+dg×3, g2=g+dg×2, g3=g+dg, g4=g, where g is the initial channel width of the outer fold and dg is the gradient change parameter of the outer fold.

4. The broadband acoustic signal amplifier based on nested spatially folded metamaterials according to claim 3, characterized in that: When the amplifier operates in the frequency range of 384Hz-720Hz, the inner folded structure (1) has a sound channel width of g1n=g2n=g3n=1mm, g4n=4mm, gn=1mm, dgn=3mm, an opening width of wn=0.75mm, a central cavity radius of r1n=4mm, an arc-shaped partition thickness of tn=0.5mm, and a number of partitions of Mn=3. The outer folded structure (2) has a sound channel width of g1=19mm, g2=13mm, g3=7mm, g4=1mm, g=1mm, dg=6mm, an opening width of w=1.5mm, a central cavity radius of R1=15mm, an arc-shaped partition thickness of t=1mm, and a number of partitions of M=6. The height of the arc-shaped partition that makes up the inner folded structure (1) and the outer folded structure (2) is h=20mm.

5. The broadband acoustic signal amplifier based on nested spatially folded metamaterials according to claim 3, characterized in that: When the amplifier operates in the frequency range of 193Hz-366Hz, the inner folded structure (1) has a sound channel width of g1n=g2n=g3n=2mm, g4n=8mm, gn=2mm, dgn=6mm, an opening width of wn=1.5mm, a central cavity radius of r1n=8mm, an arc-shaped partition thickness of tn=1mm, and a number of partitions of Mn=3. The outer folded structure (2) has a sound channel width of g1=38mm, g2=26mm, g3=14mm, g4=2mm, g=2mm, dg=12mm, an opening width of w=3mm, a central cavity radius of R1=30mm, an arc-shaped partition thickness of t=2mm, and a number of partitions of M=6. The height of the arc-shaped partition that makes up the inner folded structure (1) and the outer folded structure (2) is h=10mm.

6. The broadband acoustic signal amplifier based on nested spatially folded metamaterials according to claim 3, characterized in that: When the amplifier operates in the frequency range of 257Hz-485Hz, the inner folded structure (1) has a sound channel width of g1n=g2n=g3n=1.5mm, g4n=6mm, gn=1.5mm, dgn=4.5mm, an opening width of wn=1.125mm, a central cavity radius of r1n=6mm, an arc-shaped partition thickness of tn=0.75mm, and a partition number of Mn=3. The outer folded structure (2) has a sound channel width of g1=28.5mm, g2=19.5mm, g3=10.5mm, g4=1.5mm, g=1.5mm, dg=9mm, an opening width of w=2.25mm, a central cavity radius of R1=22.5mm, an arc-shaped partition thickness of t=1.5mm, and a partition number of M=6. The height of the arc-shaped partition that makes up the inner folded structure (1) and the outer folded structure (2) is h=15mm.

7. The broadband acoustic signal amplifier based on nested spatially folded metamaterials according to claim 2, characterized in that: The outer folded structure (2) has a 5-layer gradient folded structure with a sound channel width of g1=g+dg×4, g2=g+dg×3, g3=g+dg×2, g4=g+dg, g5=g, where g is the initial channel width of the outer fold and dg is the gradient change parameter of the outer fold.

8. The broadband acoustic signal amplifier based on nested spatially folded metamaterials according to claim 7, characterized in that: When the amplifier operates in the frequency range of 507Hz-727Hz, the inner folded structure (1) has a sound channel width of g1n=g2n=g3n=1mm, g4n=4mm, gn=1mm, dgn=3mm, an opening width of wn=0.75mm, a central cavity radius of r1n=4mm, an arc-shaped partition thickness of tn=0.5mm, and a number of partitions of Mn=3. The outer folded structure (2) has a sound channel width of g1=29mm, g2=23mm, g3=17mm, g4=11mm, g5=5mm, g=5mm, dg=6mm, an opening width of w=1.5mm, a central cavity radius of R1=15mm, an arc-shaped partition thickness of t=1mm, and a number of partitions of M=6. The height of the arc-shaped partition that makes up the inner folded structure (1) and the outer folded structure (2) is h=18mm.

9. The broadband acoustic signal amplifier based on nested spatially folded metamaterials according to claim 7, characterized in that: When the amplifier operates in the frequency range of 254Hz-367Hz, the inner folded structure (1) has a sound channel width of g1n=g2n=g3n=2mm, g4n=8mm, gn=2mm, dgn=6mm, an opening width of wn=1.5mm, a central cavity radius of r1n=8mm, an arc-shaped partition thickness of tn=1mm, and a number of partitions of Mn=3. The outer folded structure (2) has a sound channel width of g1=58mm, g2=46mm, g3=34mm, g4=22mm, g5=10mm, g=10mm, dg=12mm, an opening width of w=3mm, a central cavity radius of R1=30mm, an arc-shaped partition thickness of t=2mm, and a number of partitions of M=6. The height of the arc-shaped partition that makes up the inner folded structure (1) and the outer folded structure (2) is h=23mm.

10. The broadband acoustic signal amplifier based on nested spatially folded metamaterials according to claim 7, characterized in that: When the amplifier operates in the frequency range of 339Hz-488Hz, the inner folded structure (1) has a sound channel width of g1n=g2n=g3n=1.5mm, g4n=6mm, gn=1.5mm, dgn=4.5mm, an opening width of wn=1.125mm, a central cavity radius of r1n=6mm, an arc-shaped partition thickness of tn=0.75mm, and a partition number of Mn=3. The outer folded structure (2) has a sound channel width of g1=43.5mm, g2=34.5mm, g3=25.5mm, g4=16.5mm, g5=7.5mm, g=7.5mm, dg=9mm, an opening width of w=2.25mm, a central cavity radius of R1=22.5mm, an arc-shaped partition thickness of t=1.5mm, and a partition number of M=6. The height of the arc-shaped partition that makes up the inner folded structure (1) and the outer folded structure (2) is h=28mm.

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