Acoustic transmission enhancer and acoustic transmission enhancing system

Abstract

An acoustic transmission enhancer includes a resonance-based metamaterial. An acoustic transmission enhancement system comprising: a material in a medium; the metamaterial based on resonance is positioned on the material; and a transducer that emits acoustic waves through the medium to the material and the metamaterial.

Description

Technical Field

[0001] This disclosure relates to acoustic transmission enhancers and acoustic transmission enhancement systems. Background Technology

[0002] Patent Document 1 discloses a non-Hermitian complementary metamaterial (NHCMM) configured to coherently add a first-order-of-magnitude energy amplification to sound waves to compensate for energy loss due to wave propagation through a sample. The NHCMM is essentially an active circuit wired to a piezoelectric layer, designed to achieve negative complex effective density and negative effective sound velocity. The design disclosed in Patent Document 1 is an active system with an operational amplifier.

[0003] Non-Patent Document 1 discloses a non-Foster circuit and stability theory.

[0004] Patent document 1: US2021 / 137487.

[0005] Non-patent literature 1: Stearns SD, “Non-Foster circuits and stability theory”, IEEE International Symposium on Antennas and Propagation (APSURSI) (IEEE, 2011). Summary of the Invention

[0006] The design disclosed in Patent Document 1 has several problems.

[0007] 1. Increased power consumption. This design requires an operational amplifier, which in turn requires an additional DC power supply.

[0008] 2. Noise is a common problem with operational amplifiers. Noise from operational amplifiers interferes with the acoustic signal of interest, resulting in a lower signal-to-noise ratio.

[0009] 3. This design is relatively complex to avoid instability in the gain circuit. See Non-Patent Literature 1 for details.

[0010] 4. In some cases, the bandwidth can be very narrow. Patent Document 1 does not disclose a graph of power transfer as a function of frequency anywhere and assumes that the bandwidth is very low. This is because the conditions for simultaneously achieving negative values ​​for both the complex effective density and the complex effective sound velocity are very stringent.

[0011] This disclosure aims to address the aforementioned problems and to provide an acoustic transmission enhancer and an acoustic transmission enhancement system that enhance acoustic transmission through a material disposed in a medium.

[0012] In one embodiment, this disclosure provides an acoustic transmission enhancer comprising a resonance-based metamaterial.

[0013] In another embodiment, this disclosure provides an acoustic transmission enhancement system comprising: a material located in a medium; a resonance-based metamaterial located on the material; and a transducer that transmits sound waves through the medium toward the material and the metamaterial, wherein the system enhances acoustic transmission through the material.

[0014] This disclosure provides an acoustic transmission enhancer and an acoustic transmission enhancement system that enhance acoustic transmission through a material disposed in a medium. Attached Figure Description

[0015] Figure 1 This is a schematic cross-sectional view of an example acoustic transmission enhancer according to an embodiment of the present disclosure.

[0016] Figure 2 This is a schematic perspective view of an example resonant structure of a metamaterial according to an embodiment of the present disclosure.

[0017] Figure 3 This is a schematic perspective view of another example resonant structure of a metamaterial according to an embodiment of the present disclosure.

[0018] Figure 4 This is a schematic perspective view of another example acoustic transmission enhancer according to an embodiment of the present disclosure.

[0019] Figure 5 It is a schematic three-dimensional diagram based on the simulation model of Example 1.

[0020] Figure 6 This is a schematic three-dimensional diagram of the resonant structure used in the simulation according to Example 1.

[0021] Figure 7 The graph shows the simulation results according to Example 1, where power transfer is plotted relative to frequency.

[0022] Figure 8 It is a schematic three-dimensional diagram based on the simulation model of Example 2.

[0023] Figure 9 This is a schematic three-dimensional diagram of the resonant structure used in the simulation according to Example 2.

[0024] Figure 10The graph shows the simulation results based on Example 2 and Comparative Example 1, where power transfer is plotted relative to frequency.

[0025] Figure 11 It is a schematic plan view of the acoustic transmission enhancer based on Example 3.

[0026] Figure 12 This is a schematic diagram based on the experimental setup in Example 3.

[0027] Figure 13 This is a schematic diagram based on the experimental setup of Example 3'.

[0028] Figure 14 This is a schematic diagram based on the experimental setup of Comparative Example 2.

[0029] Figure 15 This is a schematic diagram based on the experimental setup of Comparative Example 3.

[0030] Figure 16 The graph shows the experimental results based on Example 3 and Example 3', as well as Comparative Example 2 and Comparative Example 3, where power transfer is plotted relative to frequency. Detailed Implementation

[0031] The acoustic transmission enhancer and acoustic transmission enhancement system of this disclosure are described below.

[0032] This invention is not limited to the following preferred embodiments, and can be appropriately modified without departing from the spirit of the invention. Combinations of two or more preferred features described in the following preferred embodiments also fall within the scope of this invention.

[0033] Acoustic transmission enhancer

[0034] First, an acoustic transmission enhancer according to an embodiment of the present disclosure will be described.

[0035] According to this embodiment, the present disclosure provides an acoustic transmission enhancer implemented by a material disposed in a medium, comprising a resonance-based metamaterial. The acoustic transmission enhancer according to this embodiment comprises a resonance-based metamaterial and thus can enhance acoustic transmission through the material disposed in the medium.

[0036] Figure 1 This is a schematic cross-sectional view of an example acoustic transmission enhancer according to an embodiment of the present disclosure. Figure 1 A system without metamaterials is also shown for comparison.

[0037] Due to the impedance mismatch between the medium and the material, sound waves cannot be transmitted from medium 10 (background medium) to another material 11 (aberration layer) (see [reference]). Figure 1(The central part). Sound waves emitted by transducer 12, etc., propagate through medium 10 and reach material 11, but the sound waves are reflected by material 11 and cannot propagate through material 11. In contrast, the acoustic transmission enhancer 13 according to this embodiment includes a resonance-based metamaterial 14 (see Figure 1 (the left portion), and thus can enhance acoustic transmission through the material 11 disposed in the medium 10 (see the left portion), and therefore can enhance acoustic transmission through the material 11 (see the left portion). Figure 1 (The right side portion). Sound waves emitted by transducer 12, etc., propagate through medium 10. Sound waves reaching material 11 are transmitted through material 11 due to the resonance effect of metamaterial 14. At and near the resonance frequency, metamaterial 14 undergoes strong vibrations due to the resonance effect. The resonant metamaterial 14 acts as a secondary sound source to radiate sound waves to the other side of material 11 again; otherwise, power transmission would be very limited without metamaterial 14. Therefore, the acoustic metamaterial enhances the transmission of ultrasound. In other words, metamaterial 14 reduces the reflection of sound waves by material 11. This embodiment opens up possibilities for non-invasive, wireless, and contactless acoustic transmission through aberration layers.

[0038] As described above, preferably, the metamaterial includes a resonant structure to reduce acoustic energy loss due to impedance mismatch between the medium and the material, thereby enhancing acoustic transmission through the material. Due to the presence of the resonant structure, the metamaterial can reduce acoustic energy loss caused by impedance mismatch between the medium and the material. In other words, by taking into account the impedance mismatch between the media, sound waves can be transmitted and amplified as they propagate from one medium to another.

[0039] To effectively enhance acoustic transmission, the ratio of the material's impedance Z2 to the medium's impedance Z1, Z2 / Z1, is preferably greater than 0 and less than or equal to 110,000 (excluding 1), more preferably 3 to 5,000.

[0040] Impedances Z1 and Z2 can be calculated using the following equations:

[0041] Z = √ρ × √β

[0042] Where ρ represents density and β represents bulk modulus.

[0043] Table 1 below shows example combinations of media and materials, and the impedance ratio Z2 / Z1 for each combination. Table 1 also shows whether each combination has an acoustic transmission enhancement effect on the metamaterial.

[0044] Table 1

[0045] As shown in Table 1, the inventors have confirmed that the acoustic transmission enhancement effect achieved by metamaterials can be realized over a wide range of Z2 / Z1 ratios of 110,000 or less. The acoustic transmission enhancement effect is particularly significant when the Z2 / Z1 ratio is 5,000 or less.

[0046] The acoustic transmission enhancer according to this embodiment achieves the following effects.

[0047] 1. The metamaterial according to this embodiment is a passive metamaterial and does not require an operational amplifier that requires an additional DC power supply. Therefore, compared to the design mentioned in Patent Document 1, this metamaterial requires less power consumption.

[0048] 2. Since no operational amplifier is used in this embodiment, the operational amplifier noise problem mentioned in Patent Document 1 is solved.

[0049] 3. The metamaterial according to this embodiment has a simple design and can be manufactured using current 3D printing technology.

[0050] 4. The metamaterial according to this embodiment has a wider bandwidth than complementary metamaterials (CMM) and non-Hermitian complementary metamaterials (NHCMM).

[0051] The medium is the background medium that fills the space around the material and the acoustic transmission enhancer (metamaterial). The medium can be any fluid or non-fluid. Examples include gases such as air and nitrogen, and liquids such as water, acidic aqueous solutions, alkaline aqueous solutions, blood, and organic solvents. The types of the medium before and after the material (before and after sound wave transmission) can be the same or different from each other.

[0052] The material itself is a component that impedes the transmission of sound waves (causing sound energy loss) and can be any material different from the medium. Specific examples include resin materials such as polypropylene, non-metallic materials such as bone and skin, and metallic materials (or their alloys) such as stainless steel, aluminum, silver, and gold. The material can be made from a single material or from a variety of different materials.

[0053] The form and structure of the material are unrestricted. Any form and structure beneficial to acoustic applications can be adopted. For example, the material can be a plate (layer).

[0054] The thickness of the material (its dimension in the direction of the incident wave's propagation) is unlimited. In air, the thickness can be as small as 1e-7 m if the operating frequency is 1 GHz. And in air, the thickness can be as large as 10 m if the operating frequency is 10 Hz.

[0055] The dimensions of the material (the dimensions in the direction perpendicular to the direction of travel of the incident wave) are not limited and can be set appropriately.

[0056] Metamaterials are acoustic metamaterials composed of resonant structures that resonate within a local frequency range, thus facilitating acoustic transmission through the material. Metamaterials are artificial substances whose behavior towards sound waves differs from that of natural materials. Specifically, as mentioned above, metamaterials reduce acoustic energy loss due to impedance mismatch between the medium and the material, thereby enhancing acoustic transmission through the material.

[0057] Metamaterials can be any material. These materials can include metals, nonmetals, and alloys. In this document, the term "alloy" refers to a metal made by fusing a metal with different metals and / or nonmetals. Metamaterials can be made from a single material or from multiple different materials.

[0058] Metamaterials can be placed anywhere, as long as they are on top of a material. For example, a metamaterial can be placed in front of a material (before sound waves propagate) (see [link to relevant documentation]). Figure 1 The metamaterial can be placed either on the right side of the material or behind it (after the sound waves have been transmitted), or it can be placed in front of and behind the material (before and after the sound waves have been transmitted). In either case, the metamaterial can be positioned in direct contact with the material.

[0059] The unit elements of metamaterials can have any structure. Metamaterials can include resonant structures of arbitrary shapes that resonate within a local frequency range and thus facilitate acoustic transmission through the material. Therefore, metamaterials can be designed to readily generate resonance to facilitate various structures that transmit sound through the material.

[0060] Here, the local frequency range for resonance is not limited. At a resonant peak frequency of 250 GHz (showing the frequency of transmission peak), the local frequency can be in the range of 200 GHz to 300 GHz; or at a resonant peak frequency of 500 kHz, the local frequency can be in the range of 400 kHz to 600 kHz; or at a resonant peak frequency of 40 kHz, the local frequency can be in the range of 20 kHz to 60 kHz. Each range includes boundary values.

[0061] Preferably, the resonant structure comprises a mass-and-spring based structure, which acts as a resonator and generates resonance within a local frequency range. This mass-and-spring based structure collectively generates local resonance and thus facilitates the transmission of ultrasonic waves through the material. Therefore, the mass-and-spring structure can be used as a resonator.

[0062] A mass block can be constructed such that it is not connected to any material, but is connected to a spring, while the spring can be connected to a material. The mass block and spring can be made of a single material or of multiple different materials (multimaterial). The mass block can be heavier than the spring. The mass block can be larger than, the same size as, or smaller than the spring. Alternatively, the mass block and spring can have the same dimensions. The bulk modulus and density of the spring can be less than, equal to, or greater than the bulk modulus and density of the mass block, respectively.

[0063] Figure 2 This is a schematic perspective view of an example resonant structure of a metamaterial according to an embodiment of the present disclosure.

[0064] Figure 2 The resonant structure 20 shown includes a relatively narrow spring 21 and a relatively wide mass block 22. More specifically, the resonant structure 20 has a cylindrical shape, with its narrower side adjacent to the material 23, and the resonant structure is made of a single material. The root portion, connected to the material 23 and having a relatively narrow cylindrical shape, serves as the spring 21, while the end portion, having a relatively wide cylindrical shape, serves as the mass block 22. The resonant structure 20 may be made of the same material as the material 23, or it may be made of a different material.

[0065] Figure 2 The mass block 22 shown includes a tapered portion that gradually decreases as it approaches the spring 21, but this tapered portion is not necessary. In other words, the spring 21 can be directly connected to the flat end surface of the mass block 22. Figure 2 The spring 21 and mass block 22 shown can be made of different materials.

[0066] Figure 3 This is a schematic perspective view of another example resonant structure of a metamaterial according to an embodiment of the present disclosure.

[0067] Figure 3 The resonant structure 30 shown includes a spring 31 with a relatively low bulk modulus and relatively low density, and a mass block 32 with a relatively high bulk modulus and relatively high density. More specifically, the resonant structure 30 has a cylindrical shape with a constant diameter and is made of two or more materials. The root portion containing the first material and connected to material 33 serves as the spring 31, and the end portion containing the second material serves as the mass block 32. The density and bulk modulus of the first material are both lower than those of the second material. The first material may be made of the same material as material 33, but is generally made of a different material. The second material may be made of the same material as material 33, or may be made of a different material. The density and bulk modulus of the first material may both be lower than those of material 33.

[0068] The resonant structure of the metamaterial according to this embodiment may include structures other than those based on a mass block and a spring. For example, the resonant structure may include an elongated structure with uniform mass. Specific examples include a cylindrical structure with a constant diameter and uniform mass, and an elliptical structure with uniform mass whose ends are cut along the longitudinal direction. Such a resonant structure can be directly connected to the material such that the longitudinal direction of the resonant structure intersects the material (optionally at a right angle).

[0069] The resonant structure of the metamaterial according to this embodiment can be manufactured by a 3D printer. A selective laser sintering (SLS) 3D printer is particularly preferred. The resonant structure can be formed directly on the material, or a pre-formed resonant structure can be disposed on the material (e.g., attached to the material).

[0070] The resonant structure can be symmetrically shaped about an axis parallel to the direction of travel of the incident wave. This allows the resonance peak to appear at a higher frequency compared to the asymmetrical shape described later. For example, in this case, the resonant structure can be a body of revolution. In other words, the resonant structure can have a three-dimensional shape that can be obtained by rotating any straight line about the aforementioned axis, which serves as the axis of rotation.

[0071] The resonant structure can be shaped asymmetrically about an axis parallel to the direction of travel of the incident wave. This causes the resonant peak to appear at a lower frequency compared to the case of the symmetrical shape described above. For example, in this case, the resonant structure can have the following three-dimensional shape: this three-dimensional shape can be obtained by moving a portion of a symmetrical shape (e.g., a mass block) in a direction perpendicular to the aforementioned axis.

[0072] The acoustic transmission enhancer according to this embodiment can be composed of a single resonant structure. However, preferably, the resonant structure comprises a plurality of periodically arranged resonant structures. This can also enhance acoustic transmission and bandwidth through the material disposed in the medium. As described above, the metamaterial can be a material comprising a plurality of resonant structures as unit elements (micro-units), the plurality of resonant structures being arranged at equal intervals and configured to behave as a homogeneous medium to sound waves.

[0073] The periodic arrangement can be one-dimensional, but is preferably two-dimensional. Specific examples of two-dimensional arrangements include matrix arrangements, staggered arrangements, and circular arrangements. The spacing between the resonant structures in the periodic arrangement can be, for example, 0.1 mm to 10 mm, or 100 nm to 10 µm.

[0074] The number of periodically arranged resonant structures is unlimited. However, a larger number of resonant structures results in higher sound wave transmission efficiency through the material. For example, the number can be 2 to 10,000, or 400 to 2,500.

[0075] Regarding periodic arrangement, resonant structures do not necessarily need to be arranged at equal intervals to be used as metamaterials, but the arrangement of resonant structures may affect the acoustic properties of metamaterials.

[0076] Figure 4 This is a schematic perspective view of another example acoustic transmission enhancer according to an embodiment of the present disclosure. Figure 4 A system without metamaterials is also shown for comparison.

[0077] like Figure 10 As shown, without a metamaterial, sound waves emitted by the transducer 42 and the like to the medium 40 are reflected by the material 41 disposed in the medium 40 and can hardly transmit through the material 41 (low transmission). In contrast, in the acoustic transmission enhancer 43 according to this embodiment, since a resonance-based metamaterial 44 is disposed, sound waves emitted by the transducer 42 and the like to the medium 40 transmit through the material 41 disposed in the medium 40 (high transmission). This is because the metamaterial 44 to which the sound waves are emitted resonates in a local frequency range.

[0078] Figure 4 An example of metamaterial 44 is shown, in which resonant structures 45 having the same shape and size are arranged. However, metamaterials according to this embodiment may include various types of resonant structures that have different shapes and / or different sizes from each other.

[0079] The frequency applicable to the acoustic transmission enhancer according to this embodiment, i.e., the target acoustic wave frequency for transmission enhancement, is not limited. This frequency can be any frequency beneficial to acoustic applications. Specifically, acoustic transmission at this frequency can be enhanced at any frequency of 300 GHz or lower. The frequency range can be 200 GHz to 300 GHz, 400 kHz to 600 kHz, or 20 kHz to 60 kHz. Each range includes boundary values. By changing the design and size of the resonant structure, the frequency applicable to the acoustic transmission enhancer according to this embodiment can be appropriately changed within the above ranges.

[0080] The sound waves emitted to the acoustic transmission enhancer according to this embodiment can be ultrasonic waves, such as sound waves with a frequency higher than 20 kHz.

[0081] Table 2 below shows whether metamaterials have acoustic transmission enhancement effects in continuous frequency bands.

[0082] Table 2

[0083] As shown in Table 2, the frequency can be any frequency beneficial to acoustic applications, ranging from a few hertz to a few gigahertz. The acoustic transmission enhancement effect is particularly significant in the frequency band below gigahertz.

[0084] Basically, the smaller the size of the resonant structure of a metamaterial, the higher the acoustic frequency that can be used to transmit and enhance it. Conversely, the larger the size of the resonant structure of a metamaterial, the lower the acoustic frequency that can be used to transmit and enhance it.

[0085] Acoustic transmission enhancement system

[0086] Next, an acoustic transmission enhancement system according to an embodiment of the present disclosure will be described.

[0087] The acoustic transmission enhancement system according to this embodiment includes a material disposed in a medium, a resonance-based metamaterial disposed on the material, and a transducer that emits sound waves through the medium to the material and the metamaterial, wherein the system enhances acoustic transmission through the material. The acoustic transmission enhancement system according to this embodiment includes a resonance-based metamaterial, and therefore can enhance acoustic transmission through the material disposed in the medium.

[0088] The medium, materials, and metamaterials have been described above with respect to the acoustic transmission enhancer according to this embodiment. Therefore, the transducer will be described below.

[0089] A transducer is a sound source (transmitter) that converts electrical signals into sound waves, preferably ultrasonic waves. Transducers transmit sound waves through a medium into materials and metamaterials.

[0090] The frequency of the sound waves emitted by the transducer is not limited and can be any frequency beneficial to acoustic applications. Specifically, the frequency can be any frequency of 300 GHz or less. The frequency range is preferably 1 kHz or greater and 1,000 kHz or less, more preferably 1 MHz or greater and 300 GHz or less.

[0091] The size of the transducer is not limited. Smaller size results in higher acoustic wave transmission efficiency through the material. For example, the diameter of the acoustic wave transmission section of the transducer can be from 1 mm to 100 mm, or from 20 mm to 50 mm.

[0092] The distance between the transducer and the material or metamaterial (whichever is closer to the transducer) is unlimited and can be appropriately set. For example, the distance can be from 1 mm to 100 mm, or from 1 cm to 10 m.

[0093] The incident angle of the sound waves transmitted from the transducer to the material is unrestricted. The angle range can be -1° to 1° or 9° to 11°. Here, the incident angle is 0° in the direction perpendicular to the material. Each range includes boundary values.

[0094] Example

[0095] Examples of acoustic transmission enhancers and acoustic transmission enhancement systems disclosed herein are described below in more detail. The invention is not limited to these examples.

[0096] Example 1

[0097] Figure 5 It is a schematic three-dimensional diagram based on the simulation model of Example 1.

[0098] like Figure 5 As shown, in this example, acoustic transmission is simulated in the following model: In this model, metamaterial 52 is placed on a polypropylene (PP) plate 51 placed in air 50. The PP plate 51 has a thickness of 2 mm and multiple cylindrical resonant structures 53 are regularly arranged in a 50×50 matrix on one surface of the PP plate 51. The transducer (not shown) has a diameter of 47 mm and emits a 40 kHz sound wave into the metamaterial 52.

[0099] Figure 6 This is a schematic three-dimensional diagram of the resonant structure used in the simulation according to Example 1.

[0100] like Figure 6 As shown, each resonant structure 53 has a cylindrical shape with a constant diameter and is made of two materials. The root portion serves as a spring 54, while the end portion, made of a material heavier than the spring 54, serves as a mass block 55.

[0101] Table 3 below shows the dimensions of each resonant structure 53. p is the length of one side of the square region on which each resonant structure 53 is placed. d is the diameter of the resonant structure 53. h1 is the height of the spring 54. h2 is the height of the mass block 55.

[0102] Table 3

[0103] Table 4 below shows the physical property values ​​for Tango plus FLX930 (Stratasys), a rubber-like flexible material used in 3D printers; and the physical property values ​​for Durus (Stratasys), a simulated polypropylene material also used in 3D printers. For spring 54, the physical property values ​​for Tango plus FLX930—simulated rubber—were used. For mass block 55 and polypropylene plate 51, the physical property values ​​for Durus—simulated polypropylene—were used.

[0104] Table 4

[0105] Figure 7 The graph shows the simulation results according to Example 1, where power transfer is plotted relative to frequency.

[0106] like Figure 7 As shown, this metamaterial transmits 40 kHz ultrasound waves through a 2 mm thick polypropylene plate with an acoustic power transmission rate exceeding 90%. The basic mechanism comprises two materials: a plastic cylinder that functions as a mass, and a rubber cylinder attached to the mass that functions as a spring. These two materials together generate a local resonance at 40 kHz, thus facilitating the transmission of ultrasound waves through the material.

[0107] Example 2

[0108] Figure 8 It is a schematic three-dimensional diagram based on the simulation model of Example 2.

[0109] like Figure 8 As shown, in this example, acoustic transmission is simulated in the following model: In this model, metamaterial 62 is placed within a stainless steel plate 61 placed in water 60. The stainless steel plate 61, with a thickness of 1 mm, is placed in water 60, and multiple cylindrical resonant structures 63 are regularly arranged in a 20×20 matrix on one surface of the stainless steel plate 61, with the narrow side of each cylindrical resonant structure 63 adjacent to the stainless steel plate 61. A transducer (not shown) has a diameter of 19 mm and emits 500 kHz sound waves into the metamaterial 62.

[0110] Figure 9 This is a schematic three-dimensional diagram of the resonant structure used in the simulation according to Example 2.

[0111] like Figure 9 As shown, each resonant structure 63 has a cylindrical shape, with its narrow side adjacent to a stainless steel plate 61, and the resonant structure 63 is made of a single material. The root portion serves as a spring 64, and the end portion serves as a mass block 65.

[0112] Table 5 below shows the dimensions of each resonant structure 63. p is the length of one side of the square region on which each resonant structure 63 is placed. d m It is the diameter of the 65-mass block. d s That is the diameter of spring 64. m1 It is the height of the tapered section of mass block 65. h m2 h is the height of the cylindrical portion of mass block 65. s It is the height of spring 64.

[0113] Table 5

[0114] Table 6 below shows the physical property values ​​for SUS316L—a type of stainless steel. The physical property values ​​for SUS316L are used for each resonant structure 63 and stainless steel plate 61.

[0115] Table 6

[0116] Figure 10 The graph shows the simulation results according to Example 2 and Comparative Example 1, where power transfer is plotted relative to frequency. For comparison, Figure 10 Simulation results based on Comparative Example 1, which does not have a metamaterial, are also shown. Comparative Example 1 uses [material name missing] from [other materials missing]. Figure 8 The model shown only removes metamaterial 62.

[0117] like Figure 10 As shown, simulation results indicate that the transmission rate through a 1 mm thick SUS board is at least 40%.

[0118] Example 3 and Example 3'

[0119] Figure 11 It is a schematic plan view of the acoustic transmission enhancer based on Example 3.

[0120] like Figure 11 As shown, a metamaterial 71 is formed on a 1 mm thick stainless steel plate 70 with a square shape and a side length of 41 mm using a 3D printer. Multiple resonant structures 72 are arranged regularly in a 20×20 matrix to house the metamaterial 71. Both the stainless steel plate 70 and the metamaterial 71 are made of SUS316L. The form and dimensions of each resonant structure 72 are as follows... Figure 9 As described in Table 3.

[0121] Figure 12 This is a schematic diagram based on the experimental setup in Example 3.

[0122] like Figure 12 As shown in Example 3, Figure 11 The stainless steel plate 70 and metamaterial 71, as shown, are placed in water 73 within a tank 74. A flat transducer (transmitter) 75, with a diameter of 19 mm, is positioned facing the center of the metamaterial 71, only 14 mm from the stainless steel plate 70. A pulse generator 76 is connected to the transducer 75. A receiver (transceiver) 77 is positioned behind the metamaterial 71, only 30 mm from it, and sound wave transmission is measured. The receiver 77 is connected to an oscilloscope 78, and the oscilloscope 78 is connected to a computer 79. The transducer 75 emits sound waves at 500 kHz.

[0123] Figure 13This is a schematic diagram based on the experimental setup of Example 3'.

[0124] like Figure 13 As shown, the experimental setup according to Example 3' is the same as that according to Example 3, except that the positions of the stainless steel plate 70 and the metamaterial 71 are completely reversed.

[0125] Figure 14 This is a schematic diagram based on the experimental setup of Comparative Example 2.

[0126] like Figure 14 As shown, in Comparative Example 2, neither stainless steel plates nor metamaterials are placed in the water 73 in the tank 74, and the ultrasonic waves emitted by the transducer 75 are directly received by the receiver 77.

[0127] Figure 15 This is a schematic diagram based on the experimental setup of Comparative Example 3.

[0128] like Figure 15 As shown, the experimental setup according to Comparative Example 3 is the same as that according to Example 3, except that a stainless steel plate 70 without metamaterial is used.

[0129] Figure 16 This is a graph showing the experimental results based on Examples 3 and 3', and Comparative Examples 2 and 3, where power transfer is plotted relative to frequency. Figure 16 In this context, w / AMM represents the result of Example 3; w / flipped AMM represents the result of Example 3'; w / o AMM represents the result of comparing Example 2; and w / bare plate represents the result of comparing Example 3.

[0130] like Figure 16 As shown, experimental results indicate that transmission through a 1 mm thick SUS plate is enhanced.

[0131] This specification discloses the following:

[0132] (1) An acoustic transmission enhancer realized by a material disposed in a medium, the acoustic transmission enhancer comprising a resonance-based metamaterial.

[0133] (2) The acoustic transmission enhancer according to (1), wherein the metamaterial includes a resonant structure for reducing acoustic energy loss due to impedance mismatch between the medium and the material, thereby enhancing acoustic transmission through the material.

[0134] (3) The acoustic transmission enhancer according to (2), wherein the ratio of the impedance Z2 of the material to the impedance Z1 of the medium, Z2 / Z1, is greater than 0 and less than or equal to 110,000 (excluding 1).

[0135] (4) The acoustic transmission enhancer according to (1) or (2), wherein the metamaterial comprises a resonant structure of arbitrary shape that resonates in a local frequency range and thus facilitates acoustic transmission through the material.

[0136] (5) The acoustic transmission enhancer according to (4), wherein the resonant structure is based on a mass block and a spring, the mass block and spring based structure working as a resonator and generating resonance in a local frequency range.

[0137] (6) The acoustic transmission enhancer according to (4) or (5), wherein the resonant structure is symmetrically shaped about an axis parallel to the direction of travel of the incident wave.

[0138] (7) The acoustic transmission enhancer according to (4) or (5), wherein the resonant structure is asymmetrically shaped about an axis parallel to the direction of travel of the incident wave.

[0139] (8) The acoustic transmission enhancer according to any one of (2) to (7), wherein the resonant structure comprises a plurality of periodically arranged resonant structures.

[0140] (9) An acoustic transmission enhancer according to any one of (1) to (8), wherein the acoustic transmission enhancer enhances acoustic transmission through the material at any frequency of 300 GHz or less.

[0141] (10) An acoustic transmission enhancement system comprising: a material disposed in a medium; a resonance-based metamaterial disposed on the material; and a transducer for transmitting acoustic waves through the medium to the material and the metamaterial, wherein the system enhances acoustic transmission through the material.

[0142] This specification also discloses the following:

[0143] <1> An acoustic transmission enhancer comprising a resonant metamaterial.

[0144] <2> according to <1> The acoustic transmission enhancer, wherein the metamaterial includes a resonant structure that reduces acoustic energy loss due to impedance mismatch between the medium and the material to which the metamaterial is located.

[0145] <3> according to <2> The acoustic transmission enhancer wherein the ratio of the impedance Z2 of the material to the impedance Z1 of the medium, Z2 / Z1, is greater than 0 and less than or equal to 110,000, but excluding 1.

[0146] <4> according to <3> The acoustic transmission enhancer wherein the ratio Z2 / Z1 is 3 to 5,000.

[0147] <5> according to <1> to <4> The acoustic transmission enhancer according to any one of the claims, wherein the metamaterial comprises a resonant structure of arbitrary shape that resonates within a local frequency range.

[0148] <6> according to <5> The acoustic transmission enhancer, wherein the resonant structure is a mass block and spring structure, and the mass block and spring structure serves as a resonator in the local frequency range.

[0149] <7> according to <6> The acoustic transmission enhancer wherein the mass block and spring in the mass block and spring structure are made of the same material or different materials.

[0150] <8> according to <6> or <7> In the acoustic transmission enhancer, the mass block has a higher bulk modulus and density than the spring in the mass block and spring structure.

[0151] <9> according to <5> to <8> The acoustic transmission enhancer according to any one of the claims, wherein the resonant structure is symmetrically shaped about an axis parallel to the direction of travel of the incident wave.

[0152] <10> according to <5> to <8> The acoustic transmission enhancer according to any one of the claims, wherein the resonant structure is shaped asymmetrically about an axis parallel to the direction of travel of the incident wave.

[0153] <11> according to <2> to <10> The acoustic transmission enhancer according to any one of the claims, wherein the resonant structure comprises a plurality of periodically arranged resonant structures.

[0154] <12> according to <1> to <11> The acoustic transmission enhancer according to any one of the claims, wherein the acoustic transmission enhancer is configured to enhance acoustic transmission through the material in which the metamaterial is located at any frequency of 300 GHz or less.

[0155] <13> An acoustic transmission enhancement system includes: a material located in a medium; a resonance-based metamaterial located on the material; and a transducer that transmits sound waves through the medium to the material and the metamaterial.

[0156] <14> according to <13> The acoustic transmission enhancement system, wherein the metamaterial includes a resonant structure that reduces acoustic energy loss due to impedance mismatch between the medium and the material.

[0157] <15> according to <14> In the acoustic transmission enhancement system described above, the ratio of the impedance Z2 of the material to the impedance Z1 of the medium, Z2 / Z1, is greater than 0 and less than or equal to 110,000, but excluding 1.

[0158] <16> according to <13> to <15> The acoustic transmission enhancement system according to any one of the claims, wherein the metamaterial comprises a resonant structure of arbitrary shape, the resonant structure generating resonance in a local frequency range.

[0159] <17> according to <16> In the acoustic transmission enhancement system, the resonant structure is a mass block and spring structure, which serves as a resonator within the local frequency range.

[0160] <18> according to <16> or <17> The acoustic transmission enhancement system wherein the resonant structure is symmetrically shaped about an axis parallel to the direction of travel of the incident wave.

[0161] <19> According to the claims <16> or <17> The acoustic transmission enhancement system wherein the resonant structure is asymmetrically shaped about an axis parallel to the direction of travel of the incident wave.

[0162] <20> according to <14> to <19> The acoustic transmission enhancement system according to any one of the claims, wherein the resonant structure comprises a plurality of periodically arranged resonant structures. List of reference numerals in the attached figures

[0163] 10, 40 media

[0164] Materials 11, 23, 33, and 41

[0165] 12, 42, 75 transducers

[0166] 13, 43 Acoustic transmission enhancer

[0167] 14, 44, 52, 62, 71 metamaterials

[0168] 20, 30, 45, 53, 63, 72 resonance structures

[0169] 21, 31, 54, 64 springs

[0170] Mass blocks of 22, 32, 55, and 65

[0171] 50 air

[0172] 51 Polypropylene (PP) Board

[0173] 60, 73 water

[0174] 61 and 70 stainless steel plates

[0175] 74 boxes

[0176] 76 pulse generator

[0177] 77 receiver

[0178] 78 Oscilloscope

[0179] 79 Computers

Claims

1. An acoustic transmission enhancer comprising a resonance-based metamaterial.

2. The acoustic transmission enhancer according to claim 1, wherein, The metamaterial includes a resonant structure that reduces acoustic energy loss due to impedance mismatch between the medium and the material on which the metamaterial is located.

3. The acoustic transmission enhancer according to claim 2, wherein, The ratio of the impedance Z2 of the material to the impedance Z1 of the medium, Z2 / Z1, is greater than 0 and less than or equal to 110,000, but does not include 1.

4. The acoustic transmission enhancer according to claim 3, wherein, The ratio Z2 / Z1 is between 3 and 5,000.

5. The acoustic transmission enhancer according to any one of claims 1 to 4, wherein, The metamaterial includes a resonant structure of arbitrary shape, which resonates within a local frequency range.

6. The acoustic transmission enhancer according to claim 5, wherein, The resonant structure is a mass block and spring structure, which serves as a resonator within the local frequency range.

7. The acoustic transmission enhancer according to claim 6, wherein, The mass block and spring in the mass block and spring structure are made of the same material or different materials.

8. The acoustic transmission enhancer according to claim 6, wherein, In the mass block and spring structure, the bulk modulus and density of the mass block are both higher than those of the spring.

9. The acoustic transmission enhancer according to any one of claims 5 to 8, wherein, The resonant structure is symmetrically formed about an axis parallel to the direction of travel of the incident wave.

10. The acoustic transmission enhancer according to any one of claims 5 to 8, wherein, The resonant structure is asymmetrically shaped about an axis parallel to the direction of travel of the incident wave.

11. The acoustic transmission enhancer according to any one of claims 2 to 10, wherein, The resonant structure includes multiple periodically arranged resonant structures.

12. The acoustic transmission enhancer according to any one of claims 1 to 11, wherein, The acoustic transmission enhancer is configured to enhance acoustic transmission through the material in which the metamaterial is located at any frequency of 300 GHz or less.

13. An acoustic transmission enhancement system, comprising: Material, the material being located in a medium; Resonance-based metamaterials, wherein the resonance-based metamaterials are located on the material; as well as A transducer that transmits sound waves through the medium to the material and the metamaterial.

14. The acoustic transmission enhancement system according to claim 13, wherein, The metamaterial includes a resonant structure that reduces acoustic energy loss due to impedance mismatch between the medium and the material.

15. The acoustic transmission enhancement system according to claim 14, wherein, The ratio of the impedance Z2 of the material to the impedance Z1 of the medium, Z2 / Z1, is greater than 0 and less than or equal to 110,000, but does not include 1.

16. The acoustic transmission enhancement system according to any one of claims 13 to 15, wherein, The metamaterial includes a resonant structure of arbitrary shape, which resonates within a local frequency range.

17. The acoustic transmission enhancement system according to claim 16, wherein, The resonant structure is a mass block and spring structure, which serves as a resonator within the local frequency range.

18. The acoustic transmission enhancement system according to claim 16 or 17, wherein, The resonant structure is symmetrically formed about an axis parallel to the direction of travel of the incident wave.

19. The acoustic transmission enhancement system according to claim 16 or 17, wherein, The resonant structure is asymmetrically shaped about an axis parallel to the direction of travel of the incident wave.

20. The acoustic transmission enhancement system according to any one of claims 14 to 19, wherein, The resonant structure includes multiple periodically arranged resonant structures.

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