Sensor device, imaging device, imaging method, imaging diagnostic method, and bandpass filter

Abstract

A sensor device is provided that includes an object; a metamaterial on the object to enhance transmission of acoustic waves through the object; a transducer that emits acoustic waves to the object and the metamaterial; and a receiver that receives the acoustic waves through the object and the metamaterial.

Description

SENSOR DEVICE, IMAGING DEVICE, IMAGING METHOD, IMAGING DIAGNOSTIC METHOD, AND BANDPASS FILTERCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Patent Provisional Application No. 63 / 699,397, filed September 26, 2024, the entire contents of which are hereby incorporated by referenceTECHNICAL FIELD

[0002] The present invention relates to sensor devices, imaging devices, imaging methods, imaging diagnostic methods, and bandpass filters.BACKGROUND

[0003] Patent Literature 1 discloses an ultrasonic sensor assembly configured for sensing an a target on the opposite side of a panel. The assembly includes an ultrasonic sensor, a preload structure configured for applying a load on the sensor toward the inside surface of the panel, and a coupling element that interfaces between the sensor and the inside surface of the panel. This technology utilizes a coupling element to improve transmission of acoustic waves between the sensor and a vehicle panel surface. The coupling element aims to match the acoustic impedance, to reduce reflection, and to increase energy' transfer efficiency.CITATION LIST

[0004] Patent Literature

[0005] Patent Literature 1 : U.S. Patent Publication 2017 / 0059697 AlSUMMARY OF INVENTION

[0006] Technical Problem

[0007] The structures described in Patent Literature 1 have several problems.

[0008] 1. Bulky assembly: The assembly including components such as a preload structure and a coupling element requires more space, which poses challenges when a sensor is installed in a limited space in a vehicle. Additionally, the bulkiness of these components can make it difficult to dispose multiple sensors in close proximity, affecting the effectiveness of the sensors in a limited space in a vehicle and other applications.

[0009] 2. Low detection sensitivity to acoustic waves: The ultrasonic sensor assembly disposed inside the exterior door panel of a vehicle so as not to be visible from the outside can lead to mixture of the emitted waves with reflected waves from a nearby object, causing overlapping vibrations. This complicates obstacle detection.

[0010] Adding damping elements is effective to reduce the vibrations, but hinders both the transmission and reception of acoustic waves. This may reduce the energy transfer between the converter, door panel, and transducer, reducing system sensitivity and range resolution.

[0011] The transmission efficiency of acoustic waves is affected by the heterogeneity between different media, such as air and a solid car door. This difference in material properties can lead to reflections at the interface and lower the overall acoustic energy transmitted through the boundary.

[0012] Furthermore, there are the following challenges.

[0013] 3. Energy efficiency: designing a coupling element that can transmit ultrasonic waves through a car door in an energy -efficient manner to minimize power consumption while ensuring a strong and highly reliable signal appears to be a significant challenge.

[0014] 4. Reliability and durability: ensuring the reliability’ and long-term durability of the coupling element technology used to transmit acoustic waves is essential to maintaining system functionality over long periods of time without degradation or failure.

[0015] The present invention aims to provide several application examples that can be achieved by a device capable of increasing the detection sensitivity to acoustic waves with a simple configuration.

[0016] Solution to Problem

[0017] One aspect of the present invention relates to a sensor device including: an object; a metamaterial on the object to enhance transmission of acoustic waves through the object; atransducer that emits the acoustic waves to the object and the metamaterial: and a receiver that receives the acoustic waves through the object and the metamaterial.

[0018] Another aspect of the present invention relates to a sensor device including: an object; metamaterials periodically disposed on the object to enhance transmission of acoustic waves through the object; a transducer that emits the acoustic waves to the object and the metamaterials; and a receiver that receives the acoustic waves through the object and the metamaterials.

[0019] Another aspect of the present invention relates to an imaging device including: a metamaterial configured to enhance transmission of acoustic waves through an object, wherein the object is an anatomical structure, and the metamaterial is to be attached to a surface of the anatomical structure and is configured to transmit acoustic waves into the anatomical structure.

[0020] Another aspect of the present invention relates to an imaging method including: attaching a metamaterial configured to enhance transmission of acoustic waves through an object to a surface of an anatomical structure, the anatomical structure being the object, and emitting acoustic waves to the metamaterial; receiving the acoustic waves reflected; and converting the acoustic waves received into image data and displaying the image data.

[0021] Another aspect of the present invention relates to an imaging diagnostic method including: attaching a metamaterial configured to enhance transmission of acoustic waves through an object to a surface of an anatomical structure, the anatomical structure being the object, and emitting acoustic waves to the metamaterial; receiving the acoustic waves reflected; converting the acoustic waves received into image data and displaying the image data; and determining whether a disease is present from the image data.

[0022] Another aspect of the present invention relates to a bandpass filter including a metamaterial, wherein the bandpass filter allows passage of acoustic waves of a specific frequency that pass through an object in a medium.

[0023] Advantageous Effects of Invention

[0024] The present invention can provide several application examples that can be achieved by a device capable of increasing the detection sensitivity to acoustic waves with a simple configuration.BRIEF DESCRIPTION OF DRAWINGS

[0025] FIG. 1 is a schematic cross-sectional view of an exemplary' metamaterial.

[0026] FIG. 2 is a schematic perspective view of an exemplary' metamaterial resonant structure.

[0027] FIG. 3 is a perspective view of an exemplar}' resonant structure.

[0028] FIG. 4 is a perspective view of another exemplary resonant structure.

[0029] FIG. 5 is a perspective view of another exemplary resonant structure.

[0030] FIG. 6 is a perspective view of another exemplary resonant structure.

[0031] FIG. 7 is a schematic perspective view of an exemplary configuration including periodically disposed metamaterials.

[0032] FIG. 8 is a cross-sectional view of an exemplary configuration including metamaterials (resonant structures) on a surface of an object.

[0033] FIG. 9 is a cross-sectional view of another exemplary configuration including metamaterials (resonant structures) on a surface of an object.

[0034] FIG. 10 is a cross-sectional view of another exemplary configuration including metamaterials (resonant structures) on a surface of an object.

[0035] FIG. 11 is a cross-sectional view of another exemplary configuration including metamaterials (resonant structures) on a surface of an object.

[0036] FIG. 12 is a cross-sectional view of another exemplary configuration including metamaterials (resonant structures) on a surface of an object.

[0037] FIG. 13 is a cross-sectional view of another exemplary' configuration including metamaterials (resonant structures) on a surface of an object.

[0038] FIG. 14 is a cross-sectional view of another exemplary' configuration including metamaterials (resonant structures) on a surface of an object.

[0039] FIG. 15 is a cross-sectional view of another exemplary' configuration including metamaterials (resonant structures) on a surface of an object.

[0040] FIG. 16 is a cross-sectional view of another exemplary configuration including metamaterials (resonant structures) on a surface of an object.

[0041] FIG. 17 is a schematic conceptual diagram of an exemplary configuration of the sensor device.

[0042] FIG. 18 is a schematic conceptual diagram of another exemplary configuration of the sensor device.

[0043] FIG. 19 is a schematic conceptual diagram of another exemplary configuration of the sensor device.

[0044] FIG. 20 is a schematic conceptual diagram of another exemplary configuration of the sensor device.

[0045] FIG. 21 is a schematic conceptual diagram of another exemplary' configuration of the sensor device.

[0046] FIG. 22 is a schematic perspective view of another exemplary configuration of the resonant structure.

[0047] FIG. 23 is a schematic perspective view of another exemplary configuration of the resonant structure.

[0048] FIG. 24 is a schematic conceptual diagram of another exemplary7configuration of the sensor device.

[0049] FIG. 25 is a schematic conceptual diagram of another exemplary configuration of the sensor device.

[0050] FIG. 26 is a schematic conceptual diagram of another exemplary configuration of the sensor device.

[0051] FIG. 27 is a schematic diagram of exemplary positions on a vehicle where sensor devices are to be mounted.

[0052] FIG. 28 is a schematic diagram of an exemplary configuration in which the object constituting a sensor device is a pipe through which a fluid flows.

[0053] FIG. 29 is a schematic diagram of an exemplary' configuration in which metamaterials are disposed on both the inner and outer surfaces of the pipe.

[0054] FIG. 30 is a schematic diagram of an exemplary' configuration in which a transducer and a receiver are separately disposed with respect to the pipe.

[0055] FIG. 31 is a schematic diagram of an exemplary7imaging device.

[0056] FIG. 32 is a schematic diagram of another exemplary imaging device.

[0057] FIG. 33 is a graph showing the relationship between the frequency of acoustic waves and the transmission of acoustic waves when a bandpass filter having a metamaterial is used.DETAILED DESCRIPTION OF EMBODIMENTS

[0058] Hereinafter, the sensor device of the present invention and the like are described.

[0059] The present invention is not limited to the following preferred embodiments and may be suitably modified without departing from the gist of the present invention.Combinations of two or more preferred individual features described in the following preferred embodiments are also within the scope of the present invention.

[0060] The following describes examples of a metamaterial included in the sensor device, imaging device, and bandpass filter of the present invention and used in the imaging method and the imaging diagnostic method of the present invention.

[0061] The metamaterial functions as a resonator and creates resonance in a local frequency range, thereby enhancing the transmission of acoustic waves through an obj ect in a medium.

[0062] FIG. 1 is a schematic cross-sectional view of an exemplary metamaterial. A part of FIG. 1 also shows a system without a metamaterial for comparison.

[0063] Acoustic waves cannot be transmitted from a medium 10 (background medium) to a different object 11 (aberrating layer) due to impedance mismatch between the media (see the center of FIG. 1). Acoustic waves emitted by a transducer 12 or a similar device propagate through the medium 10 and reach the object 11, but the acoustic waves are reflected by the object 11 and do not pass through the object 11. In contrast, a metamaterial 14 (see the left portion of FIG. 1) disposed can enhance transmission of acoustic waves through the object 11 in the medium 10 (see the right portion of FIG. 1). The acoustic waves emitted by the transducer 12 or the like propagate through the medium 10. The acoustic waves that have reached the object 11 pass through the object 11 due to the resonance effect of the metamaterial 14. In other words, the metamaterial 14 reduces the reflection of acoustic waves by the object 11.

[0064] Near the resonant frequency, the metamaterial 14 undergoes strong vibration due to the resonance effect. The metamaterial 14 functions as a secondary acoustic source to reemit the acoustic waves through the object 11. Without the metamaterial 14, only very limited acoustic waves can be transmitted. In this way, the metamaterial enhances the transmission of acoustic waves.

[0065] As described above, the metamaterial includes a resonant structure to address the issue of acoustic energy loss due to impedance mismatch between a medium and an object, thus enhancing the transmission of acoustic waves through an object. Owing to the presence of the resonant structure, the metamaterial can reduce acoustic energy loss caused by impedance mismatch between a medium and an object. In other words, the acousticwaves can be transmitted and enhanced while propagating from one medium to another medium by considering the impedance mismatch between the media.

[0066] The metamaterial on an object allows acoustic waves to pass through obstacles such as car bumpers and car doors. The resonant structure in the metamaterial optimizes energy7transfer efficiency, improving signal strength and reducing energy loss.

[0067] The resonant structure in the metamaterial optimizes energy transfer efficiency, improving signal strength and reducing energy' loss.

[0068] The resonant structure can be tuned for contactless transmission, high transmission levels, and a wide frequency' range from Hz to GHz.

[0069] The metamaterial may function as a resonator based on a mass and spring mechanism that generates resonance in a local frequency range.

[0070] When acoustic waves resonate at a specific frequency, they induce a vertical elongation mode in the mass and spring mechanism.

[0071] The spring and the mass may be the same size, or the spring may be relatively thin while the mass may be relatively thick.

[0072] The mass may be designed to have a relatively large diameter and the spring to have a relatively small diameter. A larger mass exhibits greater inertia, while a spring with a smaller diameter provides a stronger restoring force during deformation due to its reduced size and elastic properties.

[0073] A structure including the mass and the spring collectively gives rise to local resonance and consequently facilitates transmission of acoustic waves. Thus, the structure can be used as a resonator.

[0074] The mass may be connected to the spring while may not be connected to the object, and the spring may be connected to the object. The mass and the spring may be made of a single material or different materials (multi-material). The spring and the mass may be the same weight, or the mass may be relatively heavy while the spring may' be relatively light.

[0075] The bulk modulus and density of the spring may be smaller than or equal to the bulk modulus and density of the mass, respectively.

[0076] The resonant behavior descnbed above can also be achieved by using a singlediameter cylindrical structure with a constant diameter that functions as both a mass and a spring. This cylindrical structure with a constant diameter can exhibit effective mass-spring properties even when not including distinct components identified as a ’mass" and a “spring”.

[0077] The entire structure can be regarded to have an effective mass based on its total weight, and also exhibits elastic properties, i.e., extendability and compressibility, under applied acoustic waves.

[0078] The relationship between the mass and the elastic restoring force is an important property of the mass and spring mechanism.

[0079] In cases where the cylindrical structure with a constant diameter behaves like a mass and exhibits spring-like behavior owing to its elastic properties when extended vertically, the cylindrical structure with a constant diameter effectively functions as both the components (mass and spring) of a resonator. A clear dynamic interaction is an important factor between the inertia (effective mass) and the elasticity (behavior as a spring).

[0080] FIG. 2 is a schematic perspective view of an exemplary metamaterial resonant structure.

[0081] A resonant structure 20 shown in FIG. 2 includes a relatively thin spring 21 and a relatively thick mass 22. More specifically, the resonant structure 20 has a cylindrical shape having a thin portion to be adjacent to an object 23 on which the metamaterial is to be disposed. The relatively thin cylindrical root portion connected to the object 23 functions as the spring 21, and a relatively thick cylindrical end portion functions as the mass 22.The resonant structure 20 may be made of the same material as that of the obj ect 23 or a material different therefrom.

[0082] The mass 22 shown in FIG. 2 includes a tapered portion that gradually tapers toward the spring 21, but the tapered portion is not essential. In other words, the spring 21 may be directly connected to a flat end surface of the mass 22. The spring 21 and the mass 22 shown in FIG. 2 may be made of different materials.

[0083] The metamaterial may be made of any material. Examples of the material include metals, nonmetals, alloys and composite material. Herein, the term “alloy” refers to a metal made by fusing a metal with a different metal and / or nonmetal. The metamaterial may be made of only a single material or multiple different materials. Examples of the composite material includes those composed of resin and metal or ceramics.

[0084] A mass-spring resonator, which is a unit cell of the metamaterial, is designed to resonate at a desired frequency by controlling the design, shape, and material properties of the resonator. When parameters such as temperature and pressure affect the design, shape, and material properties of the resonator, the operating conditions of the metamaterial may change, and its object detection performance may also change.

[0085] The metamaterial preferably includes multiple unit cells having a size smaller than a wavelength of the acoustic waves. By disposing unit cells smaller than the wavelength of the acoustic waves, the metamaterial can substantially behave as a homogeneous medium.

[0086] The metamaterial resonant structure may include a structure other than the structure based on the mass and the spring. For example, the resonant structure may include an elongated structure made of a homogeneous material. Specific examples include a cylindrical structure with a constant diameter and made of a homogeneous material and an oval structure made of a homogeneous material with its end in the longitudinal direction cut. Such a resonant structure may be directly connected to an object such that the longitudinal direction of the resonant structure intersects the object (optionally at right angles).

[0087] The metamaterial resonant structure can be produced by a 3D printer. The 3D printer is particularly preferably a selective laser sintering (SLS) 3D printer. The resonant structure may be formed directly on an obj ect. or the resonant structure that has been formed in advance may be disposed on (e.g., attached to) an object.

[0088] The resonant structure may be symmetrically shaped about an axis parallel to the traveling direction of an incident wave. For example, in this case, the resonant structure may be a rotating body. In other words, the resonant structure may have a three- dimensional shape that can be obtained by rotating a line around the above-described axis as the axis of rotation.

[0089] The resonant structure may be asymmetrically shaped about an axis parallel to a traveling direction of an incident wave. In this case, the resonant structure may have a three-dimensional shape that can be obtained by shifting a portion of the symmetric shape (e.g., the mass) in a direction perpendicular to the axis parallel to a traveling direction of an incident wave.

[0090] The resonant structure may include a helical or inclined spring. The helical or inclined spring can enhance vibrational performance owing to its higher compliance and higher vibration amplitudes than pillar springs of similar size. By combining axial deformation and bending deformation, the inclined or helical spring allows for efficient transmission of ultrasonic waves with a more compact and mechanically robust resonant structure compared to thin and elongated pillar springs.

[0091] The resonant structure may also include multiple springs (at least two springs connected to the mass). The springs may include pillar, inclined, or helical springs, or combinations thereof, as well as springs made from different materials. By orienting the springs along distinct directions, the resonant structure achieves anisotropic vibrational control and stiffness across multiple axes. This multi-spring configuration enables the resonant structure to vibrate at the designed resonance frequency along specific directions, thereby enhancing the transmission efficiency of acoustic waves with directional control. The multi-spring configuration can improve vibrational performance and anisotropic control, enabling efficient transmission of acoustic waves at a target frequency.

[0092] FIGS. 3, 4, 5, and 6 are each a perspective view of an exemplary resonant structure.

[0093] Each of resonant structures 31, 32, 33, and 34 shown in FIGS. 3. 4, 5, and 6. respectively, has multiple springs (springs 35a, 35b, and 35c).

[0094] The resonant structure 31 shown in FIG. 3 has three inclined springs.

[0095] The resonant structure 32 shown in FIG. 4 has two helical springs.

[0096] The resonant structure 33 shown in FIG. 5 has two pillar springs.

[0097] The resonant structure 34 show n in FIG. 6 has two springs consisting of a pillar spring and an inclined spring.

[0098] The metamaterials may include a single resonant structure. Preferably, the metamaterials include periodically or non-periodically disposed multiple resonant structures.

[0099] The periodic arrangement may be one-dimensional arrangement but is preferably two-dimensional arrangement. Specific examples of the two-dimensional arrangement include matrix arrangement, staggered arrangement, and circular arrangement. The pitch of the periodically disposed resonant structures may be, for example, 0. 1 mm or more and 10 mm or less, or 100 nm or more and 10 pm or less.

[0100] The number of resonant structures periodically disposed is not limited. Yet, a greater number of resonant structures result in higher transmission of acoustic waves through an object. For example, the number may be 2 or greater and 10,000 or smaller, or 400 or greater and 2,500 or smaller.

[0101] Regarding the periodic arrangement, the resonant structures may not necessarily be disposed at equal intervals to function as the metamaterials, but the arrangement of the resonant structures can affect the acoustic characteristics of the metamaterials.

[0102] FIG. 7 is a schematic perspective view of an exemplary configuration including periodically disposed metamaterials. A part of FIG. 7 also shows a system without a metamaterial for comparison.

[0103] As shown in FIG. 7, without a metamaterial, the acoustic waves emitted by a transducer 42, for example, are reflected by an object 41 in a medium 40 and hardly pass through the object 41 (low transmission). In contrast, with metamaterials 44, the acoustic waves emitted by the transducer 42 or the like to the medium 40 pass through the object 41 in the medium 40 (high transmission). This is because the metamaterials 44 to which the acoustic waves were applied gives rise to resonance in a local frequency range.

[0104] FIG. 7 shows the metamaterials 44 and an exemplary configuration in which resonant structures having the same shape and the same size are disposed. Yet, the metamaterials may include multiple types of resonant structures that differ from each other in at least one of shape or size.

[0105] The object through which ultrasound is to be transmitted is not limited to a flat geometry'. The object may be planar, curved, or irregularly contoured depending on the application requirements. For example, the object may be a section of a pipeline, conduit, vessel wall, or any other structure having a convex, concave, or compound curvature.

[0106] The frequency of acoustic waves whose transmission is to be enhanced by the metamaterials is not limited and may be any frequency of interest to the acoustic application. Specifically, the transmission of acoustic waves through an object may be enhanced at any frequency of 300 GHz or less. The frequency may range from 250 GHz ± 50 GHz, 500 kHz ± 100 kHz, or 40 kHz ± 20 kHz. Each range includes the boundaryvalues. Changing the design and size of the resonant structures can appropriately change the frequency applicable to the metamaterials within the above range.

[0107] The acoustic waves to be emitted to the metamaterials may be ultrasonic waves, e.g., acoustic waves higher than 20 kHz.

[0108] The frequency can be any frequency of interest to the acoustic application, ranging from a few Hz to GHz. The acoustic transmission enhancement effect is high particularly in the frequency band lower than the GHz band.

[0109] Basically, the smaller the size of the metamaterial resonant structures, the higher the frequency of acoustic waves targeted for transmission enhancement. In contrast, the larger the size of the metamaterial resonant structures, the lower the frequency of acoustic waves targeted for transmission enhancement.

[0110] The interaction between the metamaterials on an object and incident acoustic waves is not confined to normal incidence configurations. The acoustic waves may also be directed at oblique angles. The incident angle of the acoustic waves can be controlled by either angling the object with the metamaterials or adjusting or angling the orientation of the sound source with respect to the object with the metamaterials.

[0111] Additionally, the arrangement of the metamaterial resonant structures on the surface of the object is not required to be aligned in a straight orientation. The axes of these resonant structures may be inclined at various angles relative to both the object surface and the direction of incident acoustic waves. These inclined resonant structures may be of different sizes.

[0112] In cases where the resonant structures are inclined or configured obliquely relative to the direction of incident acoustic waves, the metamaterials may experience a combination of vibration modes along with vertical elongation. This interaction enables generation of acoustic waves on the opposite side of the object.

[0113] The metamaterials are not necessarily fabricated directly on the object material; they may also be fabricated separately and then attached or affixed to the object.Preferably, energy damping or loss in the coupling or attachment between the metamaterialsand the object is minimized to ensure optimal transfer of vibrational energy from the metamaterials to the object.

[0114] Methods of attaching the metamaterials to the object may include, but are not limited to, clamping, ultrasonic welding, acoustic bonding adhesives, thin adhesive tapes, mechanical fastening, and magnetic attachment. Some of these attachment methods mayoffer flexibility- in adjusting the position of separately fabricated metamaterials on the object.

[0115] The thickness of the object surface may be uniform or exhibit vary ing thicknesses across its extent. Furthermore, the array of resonant structures is not limited to identical configurations; rather, it may include a combination of resonant structures specifically designed to accommodate the variations in thickness.

[0116] FIGS. 8, 9, 10, 11, 12, 13, 14, 15, and 16 are each a cross-sectional view of an exemplary configuration including metamaterials (resonant structures) on a surface of an object.

[0117] FIG. 8 shows an exemplary configuration in which the angle of the object 41 with the resonant structures 44 is changed so that the acoustic waves emitted by the transducer 42 are obliquely incident on the resonant structures 44.

[0118] FIG. 9 shows an exemplary configuration in which the angle of the transducer 42 is changed so that the acoustic waves emitted by the transducer 42 are obliquely incident on the resonant structures 44.

[0119] FIG. 10 shows an exemplary- configuration in which the angle of the axis of the resonant structures 44 on the surface of the object 41 is changed so that the acoustic waves emitted by the transducer 42 are obliquely incident on the resonant structures 44.

[0120] FIG. 11 shows an exemplary configuration in which the angle of the axis of the resonant structures 44 on the surface of the object 41 is changed and the inclined resonant structures 44 have different sizes so that the acoustic waves emitted by the transducer 42 are obliquely incident on the resonant structures 44.

[0121] FIG. 12 shows a process of attaching the resonant structures 44 to an attachment member 45 and attaching the attachment member 45 to the object 41.

[0122] FIG. 13 shows an exemplary configuration in which the resonant structures 44 are attached to the object 41 with the attachment member 45 in between. The attachment member 45 and the object 41 can be fixed together, for example, by mechanical fixing, fastening, or pressure.

[0123] FIG. 14 shows an exemplary configuration in which the resonant structures 44 are attached to the attachment member 45, and the attachment member 45 is attached to the object 41 using clamps 46.

[0124] FIG. 15 shows an exemplary configuration in which the object 41 has a varying thickness.

[0125] FIG. 16 shows an exemplary7configuration in which the object 41 has a varying thickness and the resonant structures 44 have different heights.

[0126] (Sensor device)

[0127] The sensor device of the present invention is described.

[0128] The sensor device of the present invention includes an object; a metamaterial on the object to enhance transmission of acoustic waves through the object; a transducer that emits the acoustic waves to the object and the metamaterial; and a receiver that receives the acoustic waves through the object and the metamaterial.

[0129] FIG. 17 is a schematic conceptual diagram of an exemplary configuration of the sensor device.

[0130] A sensor device 101 includes a plate-shaped object 141, metamaterials 144 as resonant structures on the object 141, and an acoustic wave sensor 110.

[0131] The acoustic wave sensor 110 is a device configured to function as both a transducer 111 and a receiver 112, with the transducer 111 and the receiver 112 being integrated.

[0132] The sensor device 101 detects an obstacle (person) 150 that is a detection target.

[0133] The acoustic waves (emitted waves) emitted by the transducer 111 pass through the object 141 due to the presence of the metamaterials 144. The acoustic waves that have passed through the object 141 are reflected by the person 150 (detection target). The reflected acoustic waves (reflected waves) then pass through the object 141 again and reach the receiver 112. The metamaterials 144 on the object 141 enable the reflected waves to pass through the object 141. In FIG. 17, the emitted waves are shown by solid lines and the reflected waves by dashed lines.

[0134] In this way, the transmission of acoustic waves through an object is enhanced by the metamaterials on the object. This enables suitable detection of an obstacle located beyond the object, as viewed from the transducer and the receiver.

[0135] (Another embodiment of sensor device)

[0136] In the sensor device of the present invention, the transducer and the receiver may be separate devices.

[0137] Further, the metamaterial may be spaced apart from the receiver, and the metamaterials may be spaced apart from the transducer. Even when the object is spaced apart from the receiver and the object is spaced apart from the transducer, signals can be suitably transmitted.

[0138] FIG. 18 is a schematic conceptual diagram of another exemplary' configuration of the sensor device.

[0139] Although FIG. 17 shows the sensor device 101 in which the transducer 111 and the receiver 112 are integrated, the transducer and the receiver may be separate devices.

[0140] In a sensor device 102 shown in FIG. 18, the transducer 111 and the receiver 112 are separate devices.

[0141] The transducer 111 emits acoustic waves to the object 141 and the metamaterials 144, and the receiver 112 receives the acoustic waves that have passed through the object 141 and the metamaterials 144.

[0142] The metamaterials 144 are disposed on a surface of the object 141 facing the transducer 111. Alternatively, the metamaterials 144 may be disposed on a surface of the object 141 facing the receiver 112.

[0143] In the sensor device of the present invention, the spring and the mass may be made of different materials.

[0144] FIG. 19 is a schematic conceptual diagram of another exemplary configuration of the sensor device.

[0145] In a sensor device 103 shown in FIG. 19, a spring 121 and a mass 122 that constitute each metamaterial 144 are made of different materials. In FIG. 19, the spring 121 and the mass 122 are show n with different hatches.

[0146] Preferably, the spring is made of a material having a relatively lower density7than the material of the mass, and the mass is made of a material having a relatively^ higher density than the material of the spring. For example, the spring may be made of a rubber material, and the mass may be made of a resin material (e.g., polypropylene).

[0147] In the sensor device of the present invention, the metamaterials may include multiple types of resonant structures that differ from each other in at least one of shape or size.

[0148] FIG. 20 is a schematic conceptual diagram of another exemplary configuration of the sensor device.

[0149] In a sensor device 104 shown in FIG. 20, the metamaterials include resonant structures that differ in shape and size.

[0150] FIG. 20 shows resonant structures 144a, 144b, 144c, 144d, and 144e. These resonant structures differ from each other in, for example, the spring diameter, the mass diameter, the ratio betw een the spring diameter and the mass diameter, the spring length, the mass length, or the ratio between the spring length and the mass length. In FIG. 20, all of the resonant structures have different shapes and sizes. The numbers of the respective resonant structures may differ from each other.

[0151] The presence of the metamaterials including multiple types of resonant structures can widen or narrow the frequency band of acoustic waves targeted for transmission enhancement or can adjust the frequency band of the acoustic weaves.

[0152] Changing the ratio of the numbers of the multiple resonant structures can widen or narrow the frequency band of acoustic waves where transmission is enhanced or can adjust the frequency band of acoustic waves.

[0153] The multiple resonant structures may or may not be disposed at equal intervals.

[0154] FIG. 21 is a schematic conceptual diagram of another exemplary configuration of the sensor device.

[0155] In FIG. 21, the resonant structures include large-sized resonant structures 144f and small-sized resonant structures 144g. The resonant structures 144g are neither periodically disposed nor disposed at equal intervals (the structures are randomly disposed).

[0156] FIG. 22 is a schematic perspective view' of another exemplary' configuration resonant structure.

[0157] In FIG. 22, the resonant structures include large-sized resonant structures 144f and small-sized resonant structures 144g. The resonant structures 144f and the resonant structures 144g are periodically disposed.

[0158] The resonant structures 144f and the resonant structures 144g are disposed alternately in the vertical and horizontal directions.

[0159] FIG. 23 is a schematic perspective view of another exemplary configuration of the resonant structure.

[0160] In FIG. 23, the resonant structures include large-sized resonant structures 144f and small-sized resonant structures 144g. The resonant structures 144f and the resonant structures 144g are periodically disposed.

[0161] The rows of resonant structures 144f and the rows of resonant structures 144g are alternately disposed.

[0162] In the sensor device of the present invention, the metamaterials may be on at least one side of an object.

[0163] FIG. 24 is a schematic conceptual diagram of another exemplary' configuration of the sensor device.

[0164] In a sensor device 105 shown in FIG. 24, the metamaterials 144 are disposed on both a first surface 141a and a second surface 141b of the object 141. In other words, the metamaterials are disposed on both main surfaces of the object.

[0165] Of the main surfaces of the object 141 in the sensor device 105 shown in FIG. 24, the surface closer to the acoustic wave sensor 110 is the first surface 141a, and the surface behind the first surface 141a and farther from the acoustic wave sensor 110 is the second surface 141b.

[0166] The metamaterials on the first surface may be the same as or different from the metamaterials on the second surface in shape, size, number, or the like.

[0167] The sensor device of the present invention may further include a protective member that protects the metamaterials.

[0168] Examples of the protective member include a protective film provided on the surface of each metamaterial and a casing provided to surround one or multiple metamaterials.

[0169] The protective member is disposed to protect the metamaterials from environmental influences.

[0170] FIG. 25 is a schematic conceptual diagram of another exemplary' configuration of the sensor device.

[0171] In a sensor device 106 shown in FIG. 25, a protective film 145 is provided on a surface of each metamaterial 144.

[0172] The protective film may be made of any material such as resin, metal, or composite material.

[0173] Examples of the resin include polyurethane, silicone resin, epoxy resin, acrylic resin, and fluororesin (e.g., PTFE). Examples of the protective film made of resin include an elastic member, a coating member, and a chemical-resistant film.

[0174] Examples of the metal include zinc and aluminum. Examples of the protective film made of metal include an abrasion-resistant coating.

[0175] Examples of the composite material include reinforcing materials containing glass fibers.

[0176] FIG. 26 is a schematic conceptual diagram of another exemplary' configuration of the sensor device.

[0177] In a sensor device 107 shown in FIG. 26, a casing 146 is provided to surround multiple metamaterials 144.

[0178] The casing 146 may be coupled to the acoustic wave sensor 110, and the metamaterials 144 may be disposed in a space surrounded by the acoustic wave sensor 110 and the casing 146. The metamaterials 144 surrounded by the casing 146 are protected from external impacts (such as flying stones or dirt adhesion).

[0179] The casing may be made of any material such as metal or resin.

[0180] In any of the application examples described herein, a variety of media can be used between the transducer and the metamaterials and between the receiver and the metamaterials. Examples of the media include air, water, and echo gel (gel for ultrasound examination). For example, in the below-described examples of a sensor device mounted on a pipe, a medium such as echo gel or water can be used between the transducer and the metamaterials and between the receiver and the metamaterials, depending on the requirements and settings.

[0181] (Sensor device mounted on vehicle)

[0182] In the sensor device of the present invention, the object constituting the sensor device is a part of an exterior of a vehicle, and the metamaterials, the transducer, and the receiver are disposed inside the exterior of the vehicle.

[0183] FIG. 27 is a schematic diagram of exemplary positions on a vehicle where sensor devices are to be mounted.

[0184] When the object constituting the sensor device is a part of the extenor of a vehicle, the part of the exterior of the vehicle may be at least one selected from the group consisting of a bumper, a door, and an underbody.

[0185] FIG. 27 shows the positions on a vehicle 200 where the sensor device is to be mounted, namely bumpers 210, a door 220, and an underbody 230. The actual position of the underbody 230 is not a side surface of the vehicle as shown in the figure, but is the bottom surface corresponding to the back of the figure.

[0186] At these positions on the vehicle, the metamaterials, the transducer, and the receiver are disposed inside the exterior of the vehicle. For example, in FIG. 17, the object 141 corresponds to a bumper 210, and the metamaterials 144 and the acoustic w ave sensor 110 (the transducer 111 and the receiver 112) are disposed inside the bumper 210 of the vehicle.

[0187] In FIG. 27, the bumpers 210 correspond to a front bumper and a rear bumper. The sensor device may be mounted on either or both of the front and rear bumpers.

[0188] With each arrangement, the acoustic waves emitted by a transducer in the acoustic wave sensor inside the bumper travel through the metamaterials and pass through the bumper. The acoustic waves that have passed through the bumper are reflected by a person (detection target), pass through the bumper again, travel through the metamaterials, and reach a receiver in the acoustic wave sensor.

[0189] Owing to the sensor device not exposed to the outside of the vehicle, the design of the vehicle can be improved. Furthermore, the sensor device protected by the bumper is prevented from failure due to external impacts or stimuli. In other words, the arrangement can simultaneously achieve improvement of the design of the vehicle and protection of the sensor device.

[0190] The sensor device inside the bumper or door of the vehicle enables detection of other obstacles (person, other vehicles, etc.) approaching from the front, rear, or sides of the vehicle. Detection of other obstacles can be used in autonomous driving applications and parking assistance applications.

[0191] Furthermore, the sensor device on the underbody enables detection of the road surface conditions below7the vehicle.

[0192] When the object constituting the sensor device is a part of the exterior of the vehicle, preferably, the sensor device is disposed inside the exterior of the vehicle, and not outside the exterior of the vehicle. Thus, preferably, the metamaterials are disposed inside the exterior of the vehicle, and the transducer and the receiver are disposed inside the exterior of the vehicle. Preferably, the sensor device includes an acoustic wave sensor configured to function as both a transducer and a receiver.

[0193] (Sensor device mounted on pipe, etc.)

[0194] In the sensor device of the present invention, the object may be a pipe through which a fluid flows, a tank, a fluid container, or a channel, and the sensor device may measure a flow rate of the fluid or properties of the fluid or detect bubbles in the fluid.

[0195] FIG. 28 is a schematic diagram of an exemplar}7configuration in which the object constituting the sensor device is a pipe through which a fluid flows.

[0196] A sensor device 108a shown in FIG. 28 includes a pipe 300 as an object, and a fluid flows in the pipe 300. The arrow s indicate the direction of the fluid flowing in the pipe.

[0197] Metamaterials 344 are disposed on the outer surface of the pipe 300, and an acoustic wave sensor 310 is disposed facing the metamaterials 344. The acoustic w ave sensor 310 is a device configured to function as both a transducer and a receiver.

[0198] The pipe 300 has a first surface 321, a second surface 322, a third surface 323, and a fourth surface 343 disposed sequentially from the side closer to the acoustic wave sensor 310.

[0199] The first surface 321 and the fourth surface 343 constitute the outer surface of the pipe, and the second surface 322 and the third surface 323 constitute the inner surface of the Pipe.

[0200] The metamaterials 344 are disposed on the first surface 321 constituting the outer surface of the pipe.

[0201] With this arrangement, the acoustic w aves (emitted waves) emitted by a transducer in the acoustic wave sensor 310 travel through the metamaterials 344, then pass through the first surface 321 and the second surface 322 of the pipe, and enter the pipe 300. The acoustic waves are reflected by the third surface 323 facing the second surface 322. The reflected acoustic weaves (reflected waves) then pass through the second surface 322 and the first surface 321 again, then travel through the metamaterials 344, and reach a receiver portion in the acoustic w ave sensor 310. In FIG. 28, the emitted waves are shown by solid lines and the reflected waves by dashed lines.

[0202] In the arrangement shown in FIG. 28, no metamaterial is disposed on either the third surface 323, which reflects acoustic waves, or the fourth surface 324, which is the surface behind the third surface 323. Thus, acoustic weaves are less likely to pass through the pipe, and most of the acoustic waves that have reached the third surface 323 are reflected.

[0203] The fluid flowing in the pipe may be. but not limited to, gas or liquid.

[0204] Preferably, the metamaterials, the transducer, and the receiver are disposed outside the pipe. In the case of a configuration w here the sensor device is to be mounted on the outside of the pipe, the sensor device can be retrofitted to an existing pipe. Furthermore, the sensor device can be easily maintained or replaced.

[0205] Although FIG. 28 shows an exemplary configuration in which the object is a pipe through which a fluid flows, the object may also be a tank, a fluid container, or a channel.

[0206] The sensor device can measure a flow rate of the fluid or properties of the fluid or detect bubbles in the fluid.

[0207] When the flow rate of the fluid is measured using acoustic waves (ultrasonic waves), the sensor device is a flow' meter.

[0208] Examples of the properties of the fluid to be measured include temperature, viscosity, and density. In the case of a fluid containing two or more components, the proportion of each component, the solids concentration, and the like may be measured.

[0209] When bubbles in the fluid are detected, the sensor device is an air bubble sensor.

[0210] The methods and principles of these measurements using acoustic waves may be the same as those known in the art.

[0211] FIG. 29 is a schematic diagram of an exemplary configuration in which metamaterials are disposed on both the inner and outer surfaces of the pipe.

[0212] In a sensor device 108b shown in FIG. 29, metamaterials 344a are disposed on the first surface 321 of the pipe, and metamaterials 344b are disposed on the second surface 322 of the pipe. In this case, metamaterials are disposed on both the inner surface and the outer surface of the pipe serving as the object.

[0213] Other features of the sensor device 108b show n in FIG. 29 can be similar to those of the sensor device 108a show n in FIG. 28. The metamaterials 344b disposed on the second surface 322 in addition to the metamaterial 344a on the first surface 321 enable improvement of the transmittance of acoustic weaves emitted to the pipe and the transmittance of acoustic waves reflected on the inner surface of the pipe.

[0214] FIG. 30 is a schematic diagram of an exemplary configuration in which a transducer and a receiver are separately disposed with respect to the pipe.

[0215] In a sensor device 109 shown in FIG. 30, a transducer 311 and a receiver 312 are separate devices, the transducer 311 faces the first surface 321 of the pipe, and the receiver 312 faces the fourth surface 324 of the pipe.

[0216] The metamaterials 344a are disposed on the first surface 321 of the pipe, and the metamaterials 344d are disposed on the fourth surface 324 of the pipe.

[0217] In other words, the metamaterials 344a face the transducer 311, and the metamaterials 344d face the receiver 312.

[0218] With this arrangement, the acoustic waves emitted by the transducer 311 travel through the metamaterials 344a, then pass through the first surface 321 and the second surface 322 of the pipe, and enter the pipe 300. Since the metamaterials 344d are disposed on the fourth surface 324, acoustic waves are less likely to be reflected by the third surface 323, pass through the third surface 323 and the fourth surface 324, travel through the metamaterial 344d, and reach the receiver 312.

[0219] Also with this arrangement, the sensor device can measure the flow rate of the fluid or the properties of the fluid or detect bubbles in the fluid.

[0220] Although not shown, metamaterials may be further disposed on the second surface 322 and the third surface 323 constituting the inner surface of the pipe.

[0221] (Imaging device, imaging method, imaging diagnostic method)

[0222] Next, the imaging device, imaging method, and imaging diagnostic method of the present invention are described.

[0223] The imaging device of the present invention includes a metamaterial configured to enhance transmission of acoustic waves through an object, wherein the object is an anatomical structure, and the metamaterial is to be attached to a surface of the anatomical structure and is configured to transmit acoustic waves into the anatomical structure.

[0224] The imaging method of the present invention includes: attaching a metamaterial configured to enhance transmission of acoustic waves through an object to a surface of an anatomical structure, the anatomical structure being the obj ect, and emitting acoustic waves to the metamaterial; receiving the acoustic waves reflected; and converting the acoustic waves received into image data and displaying the image data.

[0225] The imaging diagnostic method of the present invention includes: attaching a metamaterial configured to enhance transmission of acoustic waves through an object to a surface of an anatomical structure, the anatomical structure being the object, and emitting acoustic waves to the metamaterial; receiving the acoustic waves reflected; converting the acoustic waves received into image data and displaying the image data; and determining whether a disease is present from the image data.

[0226] FIG. 31 is a schematic diagram of an exemplary imaging device.

[0227] In an imaging device 401 shown in FIG. 31, metamaterials 444 are attached to the surface of the head of a human body corresponding to an anatomical structure 441.

[0228] The metamaterials 444 can enhance transmission of acoustic waves through an object, thereby transmitting the acoustic waves to the anatomical structure 441.

[0229] Furthermore, the metamaterials 444 can enhance the transmission of acoustic waves from the inside to the outside of the anatomical structure 441.

[0230] Thus, the imaging device in which metamaterials are attached to the surface of an anatomical structure has high sensitivity7in detecting acoustic waves.

[0231] The imaging device 401 preferably includes a transducer and a receiver. FIG. 31 shows that an acoustic wave sensor 410 configured to function as both a transducer and a receiver can emit acoustic waves to the metamaterials 444.

[0232] The acoustic waves (emitted waves) emitted by a transducer in the acoustic wave sensor 410 travel through the metamaterials 444, enter the anatomical structure 441, and are reflected in the anatomical structure 441. The reflected acoustic waves (reflected waves) travel through the metamaterials 444 and reach a receiver part in the acoustic wave sensor 410. In FIG. 31, the emitted waves are shown by solid lines and the reflected waves by dashed lines.

[0233] The transducer and the receiver of the acoustic wave sensor may be spaced apart from the metamaterials. This arrangement is advantageous in that it is not necessary7to apply gel or the like to the surface of the anatomical structure to enhance acoustic sensitivity and-it is not necessary7to press the acoustic wave sensor against the surface of the anatomical structure.

[0234] The space between the transducer and the receiver of the acoustic wave sensor and the metamaterials may be fdled with water, echo gel, or a different medium.

[0235] An image that reflects the internal state of the anatomical structure can be obtained by converting the received acoustic waves into image data and displaying the image data. The method for obtaining this image corresponds to the imaging method of the present invention.

[0236] The imaging device of the present invention may further include a controller that converts the received acoustic waves into image data, and a display that displays the image data.

[0237] The imaging method using acoustic waves and the principles thereof may be the same as those known in the art.

[0238] The imaging method may further include determining whether a disease is present from the image data. The imaging method including this step corresponds to the imaging diagnostic method of the present invention.

[0239] Examples of the anatomical structure include human or animal tissues such as skin, bone, or an internal organ. The anatomical structure may also be a human body part, and examples of the human body part include the head and the abdomen (skin, bone, and internal organs (e.g., the brain) of the head, and skin and internal organs (e.g., digestive organs and liver) of the abdomen). The anatomical structure may also be a part of an animal other than a human.

[0240] FIG. 32 is a schematic diagram of another exemplary imaging device.

[0241] In an imaging device 402 shown in FIG. 32, the metamaterials 444 are attached to the surface of the abdomen of a human body corresponding to an anatomical structure 442.

[0242] In FIG. 32, in order to stabilize the position of the metamaterials 444, the metamaterials 444 are disposed on a surface of a plate 450, and the plate 450 is brought into contact with the surface of the abdomen of the human body. In this case, the metamaterials 444 are not in direct contact with the surface of the abdomen of the human body corresponding to the anatomical structure 442. Still, this arrangement is also included in the attachment of the metamaterials to the surface of the anatomical structure.

[0243] (Bandpass filter)

[0244] Next, the bandpass filter of the present invention is described.

[0245] The bandpass filter of the present invention includes a metamaterial. The bandpass filter allows passage of acoustic waves of a specific frequency that pass through an object in a medium.

[0246] FIG. 33 is a graph showing the relationship between the frequency of acoustic waves and the transmission of acoustic waves when a bandpass filter having a metamaterial is used.

[0247] In FIG. 33, a transmission (power transmission) of 1 on the vertical axis indicates that all the acoustic waves are transmitted (transmittance 100%), and a transmission of 0 indicates that none of the acoustic waves are transmitted (transmittance 0%).

[0248] FIG. 33 shows that the transmission of acoustic waves of 460 kHz is 0.6 (60%), which is the maximum value, and that the bandpass fdter functions to selectively transmit acoustic waves of about 460 kHz.

[0249] The use of the bandpass fdter enables transmission of only acoustic waves in a specific frequency band and blocking of acoustic waves in the other frequency bands. The use of the bandpass filter also enables transmission and reception of acoustic waves with high acoustic waves transmittance in a compact space.

[0250] By changing the design and size of the metamaterial resonant structures, the frequency of the acoustic waves to be passed through the bandpass filter can be appropriately changed.

[0251] The design and size of the resonant structures may be changed by techniques such as changing the size of the metamaterials, changing the shape of the metamaterials, changing the number (density) of the metamaterials, or using multiple types of resonant structures that differ from each other in at least one of shape or size.

[0252] Herein, the following contents are disclosed.

[0253] <1>A sensor device including: an object; a metamaterial on the object to enhance transmission of acoustic w aves through the object; a transducer that emits the acoustic waves to the object and the metamaterial; and a receiver that receives the acoustic waves through the object and the metamaterial.

[0254] <2>The sensor device according to <1>, wherein the object is a part of an exterior of a vehicle, and the metamaterial, the transducer, and the receiver are disposed inside the exterior of the vehicle.

[0255] <3>The sensor device according to <2>, wherein the part of the exterior of the vehicle is at least one selected from the group consisting of a bumper, a door, and an underbody.

[0256] <4>The sensor device according to <1>, wherein the object is a pipe through which a fluid flows, a tank, a fluid container, or a channel, and the sensor device functions as a device that measures a flow rate of the fluid or properties of the fluid or that detects bubbles in the fluid.

[0257] <5>The sensor device according to any one of <1> to <4>, wherein the metamaterial is on at least one side of the object.

[0258] <6>The sensor device according to any one of <1> to <5>, wherein the sensor device includes an acoustic wave sensor configured to function as both the transducer and the receiver.

[0259] <7>The sensor device according to any one of <1> to <5> wherein the transducer and the receiver are separate devices.

[0260] <8>The sensor device according to any one of <1> to <7>, wherein the metamaterial functions as a resonator based on a mass and spring mechanism that generates resonance in a local frequency range.

[0261] <9>The sensor device according to any one of <1> to <8>, wherein the metamaterial includes multiple types of resonant structures that differ from each other in at least one of shape or size.

[0262] <10>The sensor device according to any one of <1> to <9>, wherein the metamaterial includes multiple unit cells having a size smaller than a wavelength of the acoustic waves.

[0263] <11>The sensor device according to any one of <1> to <10>, further including a protective member that protects the metamaterial.

[0264] <12>A sensor device including: an object; metamaterials periodically disposed on the object to enhance transmission of acoustic waves through the obj ect; a transducer that emits the acoustic waves to the object and the metamaterials; and a receiver that receives the acoustic waves through the object and the metamaterials.

[0265] <13>An imaging device including: a metamaterial configured to enhance transmission of acoustic waves through an object, wherein the object is an anatomical structure, and the metamaterial is to be attached to a surface of the anatomical structure and is configured to transmit acoustic waves into the anatomical structure.

[0266] <14>The imaging device according to <13>. wherein the anatomical structure includes a first anatomical structure to which the metamaterial is to be attached and a second anatomical structure which is different from the first anatomical structure and to which acoustic waves are transmitted.

[0267] <15>The imaging device according to <13> or <14>, wherein the anatomical structure is skin, bone, or an internal organ of a head or an abdomen of a human or an animal.

[0268] <16>An imaging method including: attaching a metamaterial configured to enhance transmission of acoustic waves through an object to a surface of an anatomical structure, the anatomical structure being the object, and emitting acoustic waves to the metamaterial;receiving the acoustic waves reflected; and converting the acoustic waves received into image data and displaying the image data.

[0269] <17>An imaging diagnostic method including: attaching a metamaterial configured to enhance transmission of acoustic waves through an object to a surface of an anatomical structure, the anatomical structure being the object, and emitting acoustic waves to the metamaterial; receiving the acoustic waves reflected; converting the acoustic waves received into image data and displaying the image data; and determining whether a disease is present from the image data.

[0270] <18>A bandpass filter including a metamaterial, wherein the bandpass filter allows passage of acoustic waves of a specific frequency that pass through an object in a medium.REFERENCE SIGNS LIST10, 40 medium11, 41 object (aberrating layer)12, 42 transducer14, 20, 31, 32, 33, 34, 44 resonant structure (metamaterial)21, 35a, 35b, 35c spring22 mass23 object45 attachment member46 clamp101, 102, 103, 104, 105, 106, 107, 108a, 108b, 109 sensor device110 acoustic wave sensor111 transducer112 receiver121 springmass object a first surface of object b second surface of object , 144a, 144b, 144c, 144d, 144e, 144f, 144g resonant structure (metamaterial) protective film casing obstacle (person) vehicle bumper door underbody pipe acoustic wave sensor transducer receiver first surface of pipe second surface of pipe third surface of pipe fourth surface of pipe , 344a, 344b, 344d resonant structure (metamaterial) , 402 imaging device acoustic wave sensor , 442 anatomical structure resonant structure (metamaterial) plate

Claims

CLAIMS1. A sensor device comprising: an object; a metamaterial on the object to enhance transmission of acoustic waves through the object; a transducer that emits the acoustic waves to the object and the metamaterial; and a receiver that receives the acoustic waves through the object and the metamaterial.

2. The sensor device according to claim 1, wherein the object is a part of an exterior of a vehicle, and the metamaterial, the transducer, and the receiver are disposed inside the exterior of the vehicle.

3. The sensor device according to claim 2, wherein the part of the exterior of the vehicle is at least one selected from the group consisting of a bumper, a door, and an underbody.

4. The sensor device according to claim 1, wherein the object is a pipe through which a fluid flows, a tank, a fluid container, or a channel, and the sensor device functions as a device that measures a flow rate of the fluid or properties of the fluid or that detects bubbles in the fluid.

5. The sensor device according to claim 1, wherein the metamaterial is on at least one side of the object.

6. The sensor device according to claim 1, wherein the sensor device comprises an acoustic wave sensor configured to function as both the transducer and the receiver.

7. The sensor device according to claim 1 , wherein the transducer and the receiver are separate devices.

8. The sensor device according to claim 1, wherein the metamaterial functions as a resonator based on a mass and spring mechanism that generates resonance in a local frequency range.

9. The sensor device according to claim 1, wherein the metamaterial includes multiple types of resonant structures that differ from each other in at least one of shape or size.

10. The sensor device according to claim 1, wherein the metamaterial includes multiple unit cells having a size smaller than a wavelength of the acoustic waves.

11. The sensor device according to claim 1, further comprising a protective member that protects the metamaterial.

12. A sensor device comprising: an object; metamaterials periodically disposed on the object to enhance transmission of acoustic waves through the object; a transducer that emits the acoustic waves to the object and the metamaterials; and a receiver that receives the acoustic waves through the object and the metamaterials.

13. An imaging device comprising: a metamaterial configured to enhance transmission of acoustic waves through an object, wherein the object is an anatomical structure, and the metamaterial is to be attached to a surface of the anatomical structure and is configured to transmit acoustic waves into the anatomical structure.

14. The imaging device according to claim 13, wherein the anatomical structure comprises a first anatomical structure to which the metamaterial is to be attached and a second anatomical structure which is different from the first anatomical structure and to which acoustic waves are transmitted.

15. The imaging device according to claim 13, wherein the anatomical structure is skin, bone, or an internal organ of a head or an abdomen of a human or an animal.

16. An imaging method comprising: ataching a metamaterial configured to enhance transmission of acoustic waves through an object to a surface of an anatomical structure, the anatomical structure being the object and emiting acoustic waves to the metamaterial; receiving the acoustic waves reflected; and converting the acoustic waves received into image data and displaying the image data.

17. An imaging diagnostic method comprising: ataching a metamaterial configured to enhance transmission of acoustic waves through an object to a surface of an anatomical structure, the anatomical structure being the object, and emiting acoustic waves to the metamaterial; receiving the acoustic waves reflected; converting the acoustic waves received into image data and displaying the image data; and determining whether a disease is present from the image data.

18. A bandpass filter comprising: a metamaterial, wherein the bandpass filter allows passage of acoustic waves of a specific frequency that pass through an object in a medium.

Images