Impedance matching device, converter device and method for manufacturing an impedance matching device

Abstract

Impedance matching device for adjusting a sound characteristic impedance with: an impedance matching body (12) with a first side (14) and an opposite second side (16), wherein the impedance matching device is configured to match a sound characteristic impedance of a medium contacted on the second side (16) to a sound characteristic impedance of a transducer (48) contacted on the first side (14); wherein the impedance matching body (12) comprises microstructures (22) which have a structural extent (26) of at most 500 nm along at least one spatial direction; the microstructures (22) form a lattice structure extending along a direction perpendicular to a sound transmission direction (18a, 18b) between the first side (14) and the second side (16) of the impedance matching body (12) in the impedance matching body (12); or wherein the microstructures (22) define an acoustic path (34) between the first side (14) and the second side (16), wherein a material of the microstructures (22) has a higher acoustic characteristic impedance than the impedance matching body (12) in a region of the acoustic path (34), wherein the acoustic path (34) provides a time extension for sound transmitted through the acoustic path (34) compared to a direct connection between the first side (14) and the second side (16).

Description

[0001] The present invention relates to an impedance matching device, a transducer device with such an impedance matching device, a system with said transducer device, and a method for generating an impulse response. The present invention further relates to acoustic characteristic impedance matching and, in particular, to a system for matching an acoustic characteristic impedance.

[0002] Acoustic impedance describes the resistance of a medium to the acoustic flux created by an applied acoustic pressure. At interfaces between materials with different acoustic impedances, a portion of the acoustic energy is reflected, the proportion of which is essentially determined by the magnitude of the acoustic impedance step. Consequently, the energy transferable between the transducers and the acoustic load medium decreases, and the system's efficiency is reduced. Typical transducers with corresponding acoustic impedances are based on piezoceramics (acoustic impedance approximately 33 MRayl = 33 Ns / m). 3[1]) or piezocomposites (approximately 7 MRayl [2]). Other typical transducers are based on piezoelectric thin-film systems and membrane transducers, such as CMUT (capacitive micromachined ultrasonic transducer), whose acoustic impedances depend on the structural dimensions (approximately 1 to 5 MRayl [3]). Typical load media are water (1.48 MRayl [4]), human tissue (approximately 1.5 MRayl [4]), and air (approximately 427 MRayl [1]). For optimized energy transfer, especially in air, acoustic matching layers are essential.

[0003] Typically, layered systems for matching the acoustic impedance are fabricated from conventional or composite materials with the most suitable acoustic impedance. The acoustic impedance Z depends on the density ρ and the speed of sound c of the material: Z=cρ

[0004] Fig. Figure 9 shows three different methods for matching the acoustic characteristic impedance. So-called Single Step Matching Systems (SMS) insert a single impedance step between the ultrasonic transducer side (e.g., CMUT) and the medium side (load). Multiple Step Matching Systems (MMS) consist of two or more impedance steps. Gradient Matching Systems (GMS) describe an exponential impedance curve, which enables the best transmission efficiency. Fig. Figure 9 shows a graph where the thickness D of the matching layer between a CMUT (D = 0) and the load side or medium side (D = max) is plotted on the abscissa. The acoustic characteristic impedance Z, which is reduced between the CMUT and the medium in this diagram, is plotted on the ordinate.

[0005] This curve also shows that the influence of the acoustic impedance on the transmittance increases the closer one gets to the medium side within the matching layer system. In the example above, the matching layer system must therefore achieve the lowest possible acoustic impedances, which is not achievable with known concepts or only with significant drawbacks. Aerogels [5] offer a solution. These achieve a very low acoustic impedance, but are highly diffractive and can only be applied in individual steps (MMS) with interposed bonding materials, which in turn disrupt the transmittance behavior. Composite materials made of embedded particles in a matrix [6] have similar disadvantages.

[0006] There are numerous microstructured materials that can be fabricated using methods from the semiconductor industry. These methods include coating processes, lithography, and etching. For example, an acoustic impedance matching was achieved using these three processes to structure silicon oxide on a silicon wafer. Subsequently, a polymer was applied using a coating process and fixed to an ultrasonic transducer [7]. In another example, anisotropic etching processes were used to separate silicon into posts with a high aspect ratio, and the spaces between were then filled with epoxy resin (composite) to achieve an acoustic impedance matching [8]. Gradual transitions are possible with these methods. In one example, round, tapered silicon rods were fabricated and then embedded in epoxy [9].Another example of gradual acoustic impedance matching uses an unspecified micromachining technique to create a structured layer system of copper, PZT (lead zirconate titanate), and parylene

[10] .

[0007] However, the structures produced using known methods suffer from low efficiency.

[0008] DE 10 2008 014 120 A1 describes a use of nanoscale particles in a polymer matrix.

[0009] EP 1 298 642 A2 describes an ultrasound probe with a transducer element and an acoustic matching layer.

[0010] US 2016 / 0155433A1 describes an adaptation layer for improving ultrasound transmission between an ultrasound source and a target.

[0011] EP 1 477 778 A1 describes an acoustic matching layer, which in turn comprises a first layer and a second layer.

[0012] US 5 974 884 A refers to an acoustic matching layer in an ultrasound probe.

[0013] US 2002 / 0 161 301 A1 describes an impedance matching layer for ultrasound transducers with a gradual impedance.

[0014] Therefore, desirable would be acoustic characteristic impedance matching devices that enable highly efficient adjustment of the acoustic characteristic impedance.

[0015] One object of the present invention is therefore to provide a sound characteristic impedance matching device, a transducer device, a system with such a transducer device and a method for manufacturing a sound characteristic impedance matching device that enable efficient sound characteristic impedance matching.

[0016] This problem is solved by the subject matter of the independent patent claims.

[0017] The inventors have recognized that by forming microstructures with small dimensions in the sub-micrometer range, an extremely precise and therefore efficient acoustic impedance matching can be achieved.

[0018] According to one embodiment, an impedance matching device for adapting a characteristic acoustic impedance comprises an impedance matching element with a first side and an opposing second side. The impedance matching device is designed to match the characteristic acoustic impedance of a medium contacted at the second side to the characteristic acoustic impedance of a transducer contacted at the first side. The impedance matching element comprises microstructures having a structural extent of at most 500 nanometers along at least one spatial direction.The microstructures form a lattice structure extending along a direction perpendicular to a sound propagation direction between the first and second sides of the impedance matching body; and / or the microstructures define an acoustic path between the first and second sides, wherein a material of the microstructures has a higher acoustic characteristic impedance than the impedance matching body in a region of the acoustic path, the acoustic path providing a time extension for sound transmitted through the acoustic path compared to a direct connection between the first and second sides.

[0019] According to one embodiment, a method for manufacturing an impedance matching device comprises a step involving the provision of an impedance matching body having a first and an opposing second side, configured to match a characteristic acoustic impedance of a medium contacted on the first side to a characteristic acoustic impedance of a transducer contacted on the second side;such that the impedance matching body comprises microstructures having a structural extent of at most 500 nm along at least one spatial direction. The method is carried out such that providing the impedance matching body includes manufacturing it, wherein the manufacturing includes generating the microstructures as a lattice structure, such that the lattice structure is formed from an impedance matching material of the impedance matching body and defines cavities extending along the direction perpendicular to a sound propagation direction in the impedance matching body, wherein the cavities have a polygonal cross-section;and / or that the provision of the impedance matching body includes its manufacture, wherein the manufacture includes the creation of the microstructures, which is carried out such that the microstructures define an acoustic path between the first side and the second side, such that a material of the microstructures has a higher acoustic characteristic impedance than the impedance matching body in a region of the acoustic path, such that the acoustic path provides a time extension for sound transmitted through the acoustic path compared to a direct connection between the first side and the second side.

[0020] Further advantageous embodiments are the subject of the dependent patent claims.

[0021] Examples of implementation are explained below with reference to the accompanying drawings. These show: Fig. 1 a schematic block diagram of an impedance matching device for matching a sound characteristic impedance according to an exemplary embodiment; Fig. 2 a schematic side section view of an impedance matching device according to an embodiment in which a plurality of microstructures are arranged as branched channel structures; Fig. 3 a schematic side section view of an impedance matching device according to an embodiment in which the microstructures are formed as structures tapering towards one side of a matching body; Fig. 4a a schematic side section view of an impedance matching device according to an embodiment in which the impedance matching body is formed such that the microstructures form a hexagonal lattice structure; Fig. 4b a schematic side section view of an impedance matching device according to an embodiment in which the microstructures form a hexagonal / triangle pattern; Fig. 4c a schematic side section view of an impedance matching device according to an embodiment in which the microstructures are arranged in a triangular grid pattern, so that cavities have a triangular shape; Fig. 4d a schematic side section view of an impedance matching device according to an embodiment in which the microstructures form a lattice structure according to a diamond pattern; Fig. 5 a schematic side section view of an impedance matching device according to an embodiment in which the microstructures define an acoustic path; Fig. 6 a schematic block diagram of a converter device according to an exemplary embodiment; Fig. 7 a schematic block diagram of a system according to an exemplary embodiment; Fig. 8 a schematic flowchart of a method according to an embodiment for manufacturing an impedance matching device; and Fig. 9 a schematic representation of three known methods of matching the acoustic characteristic impedance.

[0022] Before the following exemplary embodiments are explained in detail with reference to the drawings, it should be noted that identical, functionally equivalent or equivalent elements, objects and / or structures in the different figures are provided with the same reference numerals, so that the description of these elements shown in different exemplary embodiments is interchangeable or can be applied to each other.

[0023] Fig. Figure 1 shows a schematic block diagram of an impedance matching device 10 for matching a characteristic acoustic impedance. The impedance matching device comprises an impedance matching body 12 with a first side 14 and a second side 16. The sides 14 and 16 are arranged opposite each other. The impedance matching device can be configured to allow a sound, i.e., an acoustic wave, to travel from side 14 to side 16 along a sound propagation direction 18a and / or to allow a sound wave to travel from side 16 to side 14 along an opposite sound propagation direction 18b. For example, the sound wave can be generated by a transducer that can be made in contact with side 14. Side 16 can be made in contact with a medium, such as a human body, a liquid, air, or the like.The impedance matching device 10 can be configured to match the acoustic impedance of the medium to the acoustic impedance of the transducer and / or vice versa. For this purpose, the impedance matching element 12 can, for example, have an acoustic impedance in a region on side 14 that is matched to the transducer and, furthermore, in a region on side 16, an acoustic impedance that is matched to the target medium.

[0024] This may result in the impedance matching element having a higher acoustic impedance in the area of ​​page 14 than in the area of ​​page 16, although this is not necessary.

[0025] The impedance matching body 12 comprises microstructures, for example, branched microstructures 221 and 222 and / or in-plane microstructures 223. The microstructures 221, 222, and / or 223 can be formed as cavities in a material of the impedance matching body 12, and these cavities can be filled or unfilled. The filling of the cavities can consist entirely or partially of a different material than a base material or the remaining material 24 of the impedance matching body 12. This means that the microstructures 221 to 223 can be understood as a cavity, a channel structure, and / or an inclusion in the material 24.

[0026] The microstructures 221 to 223 can each be individually or collectively formed such that they have a structural extent 261, 262 and / or 263 along at least one spatial direction, which is at most 500 nanometers, preferably at most 300 nanometers, and particularly preferably at most 100 nanometers. The structural extent 261, 262 and / or 263 can be understood as the longest distance between any two points on an outer surface of the microstructure, wherein the two points are opposite each other in a cross-section of the microstructure 221 to 223. The structural extents can be arranged along any spatial direction x, y, and / or z. If the microstructure is, for example, a tube-like structure, the points can be arranged in a longitudinal or cross-sectional section, wherein the longitudinal section is, for example, defined by a plane formed by the diameter of the tube structure.In simplified terms, the structural extent of one or more microstructures can be a dimension perpendicular to an axial direction of the respective microstructure. One idea of ​​the present embodiments lies in utilizing the resolution capability of a method described herein, which can be, for example, 100 nm or less, to fabricate structures precisely, i.e., with high resolution.

[0027] In simplified terms, in such a case the structural extent can be the diameter of a round microstructure 22.

[0028] Microstructure 222 can be fluidically coupled to microstructure 221, such that the average value of a volume occupied by microstructures 221 and 222 increases from page 14 to page 16, or alternatively decreases; that is, the average value of the acoustic characteristic impedance can increase or decrease towards page 14, or alternatively remain constant, as is the case in connection with the Fig. As described in sections 4a to 4d, this can cause a variable density ρ of material 24 and thus a change in the acoustic impedance between sides 14 and 16. If a material or filling of the microstructures 221 and 222 has a higher density than material 24, the acoustic impedance of the impedance matching device 10 can increase from side 14 to side 16. If the density is lower, for example, a decreasing acoustic impedance can be obtained along the sound transmission direction 18a. This means that the microstructures can have a first impedance matching material and that a second impedance matching material, for example material 24, can be arranged in intermediate regions between the microstructures. The microstructures can be made, for example, of a cured polymer material or a metal material. Alternatively, any other material can be used.The polymer and / or metal materials described can be precisely processed and thus used directly as microstructures, as described in connection with the manufacturing processes described herein. Alternatively, such structures can also serve as templates or negative molds to enable the reproduction of other materials.

[0029] As an alternative to an arrangement parallel or oblique to a sound transmission direction 18a or 18b, at least one microstructure can also be arranged perpendicular to this, for example parallel to an x-direction, which may be arranged perpendicular to a surface normal of the first side 14 and / or the second side 16.

[0030] By forming microstructures with a defined structural extent of at most 500 nanometers, preferably at most 300 nanometers or preferably at most 100 nanometers, an extremely fine and thus precise adjustment of the acoustic characteristic impedance along the sound transmission direction 18a and / or 18b can be achieved. This enables efficient operation of the impedance matching device even with small dimensions of the impedance matching device 10.

[0031] Exemplary implementations enable a continuous transition between the respective impedance values, for example, between the medium and the transducer, which is difficult or impossible to achieve in known concepts. These implementations provide concepts for an acoustic impulse response and its manufacturing processes, for example, or even primarily, using multiple photon absorption lithography to create layer systems that match the acoustic impedance between the transducer and the medium. One goal is ideal coupling of the acoustic energy from the transducer to the load medium (transmission case) and / or from the load medium to the transducer (reception case).

[0032] Fig. Figure 2 shows a schematic side-section view of an impedance matching device 20 according to an embodiment, in which a plurality of microstructures 22 iwith i = 1,..,6, arranged as branched channel structures between sides 14 and 16, with a high number of more than 6 microstructures. For example, a single channel structure 221 in the region of side 14 can branch into a multitude of channel structures, similar to a river delta. A material or the absence of material can be described as at least a local material density ρ2, which differs from a material density ρ1 of material 24.

[0033] The increasing volume fraction of microstructures 22 i enables an overall density of the impedance matching body 10 that is increasingly influenced by the microstructures 22 along the direction of sound transmission 18a, which can influence or determine the characteristic sound impedance and thus describes an increasing influence of such a material on the characteristic sound impedance.

[0034] The microstructures 22 can define cavities. The effective material density of the impedance matching body 12 can vary monotonically between sides 14 and 16 due to the cavities. The impedance matching material 24 with a density ρ1 can be increasingly permeated by the impedance matching material ρ2, so that a variable effective density of the impedance matching body is obtained on average over a space. The monotonous increase or decrease in the volume of the microstructures can thus lead to a monotonous change in the density of the material 24 in order to achieve the matching of the acoustic characteristic impedance. The cavities can, for example, be formed or enclosed by the microstructures. Alternatively or additionally, at least one of the microstructures 22 can define a region outside a cavity, so that the cavity is formed away from the microstructures 22.

[0035] As can be seen from the Fig. As shown in Figure 2, the microstructures can define 22 branched microchannels, the number of which is monotonically variable between pages 14 and 16 in order to effect the change in the density of the material 24.

[0036] In other words, it shows Fig. Two microcavities are located in a layered system whose effective density, and thus acoustic impedance, is modified by cavities, channels, or inclusions. The desired acoustic impedance profile can be generated by interconnected cavities 22. The largest number of channels, and therefore the lowest acoustic impedance, can be arranged on the medium side of the layered system, i.e., side 16.

[0037] Fig. Figure 3 shows a schematic side-section view of an impedance matching device 30 according to an embodiment, in which the microstructures are formed as structures tapering towards side 14. The tapering structures can form areas 28i exhibit minimal extent, with areas 28 i minimal extent refers to the structural extent. For example, the microstructures 22 i The microstructures taper conically, such that the regions 28 can represent the ends or tips of the conical structures. According to other embodiments, the microstructures are formed individually or in combination, for example, in a pyramidal, conical, or otherwise tapered shape.

[0038] In other words, illustrates Fig. Figure 3 shows an embodiment with tapered structures in which the main material 24 is subdivided into conically tapered structures, the tapering of the material 24 being possible towards side 16. The tapering can begin directly at sides 14 and 16, or alternatively be spaced apart from them. The desired acoustic impedance profile is achieved, for example, by several conically tapered volumes of the microstructures 22. i This can result in the lowest acoustic impedance of the impedance matching body being located on side 16.

[0039] While the exemplary implementations according to the Fig. 2 and / or the Fig. 3 can be used as GMS adaptation structures, the microstructures 22 can also be used as SMS and / or MMS according to other embodiments.

[0040] Fig. Figure 4a shows a schematic side-section view of an impedance matching device 40a, in which the impedance matching body is configured such that the microstructures 22 form a lattice structure extending along a direction perpendicular to the sound transmission directions 18a and / or 18b. For example, within the impedance matching body 12, there is no change in the mean density and / or the characteristic acoustic impedance from side 14 to side 16 and vice versa. This means that the impedance matching body 12 can have an average unchanged or constant characteristic acoustic impedance, which, for example, is lower than the higher of the characteristic acoustic impedances located at sides 14 and 16 and / or higher than the lower of these characteristic acoustic impedances. For example, the microstructures 22 in the depicted side section can form a hexagonal lattice or a honeycomb structure.According to one embodiment, the impedance matching device 40a enables SMS.

[0041] Fig. Figure 4b shows a schematic side-section view of an impedance matching device 40b according to an embodiment in which the microstructures form a hexagonal / triangular pattern, for example by forming several in-plane microstructures, such as the microstructure 221 perpendicular to the sound transmission directions 18a and / or 18b and several microstructures arranged in different directions perpendicular to it, which diagonally intersect the in-plane microstructure, either the microstructure 222 and / or 223, which extend in an oblique arrangement between the sides 14 and 16.

[0042] Fig. Figure 4c shows a schematic side-section view of an impedance matching device 40c according to an embodiment, in which the microstructures are arranged in a triangular grid pattern, such that cavities 32 have a triangular shape in the illustrated side-section view. The microstructures 22 can, for example, be formed from the material 24, and the cavities 32 can represent filled or unfilled spaces.

[0043] Fig. Figure 4d shows a schematic side section view of an impedance matching device 40d according to an embodiment in which the microstructures 221 to 223 also form a lattice structure, wherein the lattice structure is formed according to a diamond pattern.

[0044] The impedance matching devices 40a, 40b, 40c and / or 40d can have a substantially homogeneous or constant acoustic characteristic impedance between sides 14 and 16. Exemplary embodiments provide that an impedance matching device has an impedance matching element that is formed in multiple layers and has at least a first layer and a second layer arranged next to each other. The first layer can have a first layer characteristic impedance and the second layer can have a second layer characteristic impedance, wherein the two layer characteristic impedances are the same, but preferably different from each other. For this purpose, identical patterns according to the Fig. 4a to 4d can be used, for example based on different opening cross-sections of the cavities 32 and / or different patterns can be used, for example by arranging different impedance matching bodies 12.

[0045] According to the Fig. 4a to 4d, the microstructures 22 can form a lattice structure, arranged along a direction perpendicular to the sound transmission directions and extending along this direction, for example, along the x-direction. The cavities 32 can extend along the same or a different direction perpendicular to the sound transmission directions 18a and 18b in the impedance matching body, for example, along the y-direction. Based on an arrangement of the microstructures 22, the cavities can have a polygonal cross-section; alternatively, the cross-section can also be formed according to a freeform surface, be elliptical, or even circular.

[0046] In other words, they show Fig. 4a to 4c describe the implementation of a microlattice. The matching layer system comprises a scaffold-like lattice with variable scaffold elements. The microlattices mentioned are in the Fig. 4a to 4d are shown as cross-sectional images of various grid structures, whereby Fig. 4a a hexagonal lattice, Fig. 4b a hexagonal / triangular grid, Fig. 4c a triangular grid and Fig. Figure 4d shows a diamond grating. The gratings can be arranged in grating planes, which can, for example, run parallel to pages 14 and / or 16. An impedance matching device can have one or more grating planes. The desired acoustic impedance profile can be generated by differently oriented and connected connectors. The acoustic impedance can be further modified by changing the spacing and / or grating structures and / or connector thicknesses. The grating structures can be two-dimensional or three-dimensional. Three-dimensional grating structures can be characterized by changing the grating constant and / or the thickness and shape of the connections. This allows for high stiffness compared to tapered structures and / or easy processing with the method, as the structure can be easily implemented with a developer solution.

[0047] Fig. Figure 5 shows a schematic side-section view of an impedance matching device 50 according to an embodiment, in which the microstructures 221 to 223 define an acoustic path 34 between sides 14 and 16. For example, the acoustic path 34 can pass through the cavity 32 defined by the microstructures 221 to 223. A vacuum, a fluid, for example a gas, and / or a solid can be arranged in the cavity 32, wherein preferably a material of the microstructures 221 to 223 has a higher acoustic impedance than the impedance matching body 12 in a region of the acoustic path, for example the cavity 32. Compared with a direct or shortest path 36 between sides 14 and 16, the acoustic path 34 can provide a longer travel time for sound transmitted through the acoustic path 34.The propagation delay can be achieved by extending the path length compared to the direct connection 36. This means that the longer path length of the acoustic path 34 results in a propagation delay and thus a phase shift. According to one embodiment, the acoustic path 34 can have a plurality or multiple path segments 381 to 384. Although the impedance matching device 50 is shown with four path segments 381 to 384 arranged in series, a different number of path segments—at least one, at least two, at least three, at least five, for example six, eight, or ten or more—can be implemented. Parallel path segments can also be arranged with respect to one or more path segments.

[0048] Path segments 381 to 384 can be arranged individually, in groups, or collectively perpendicular to the sound propagation directions 18a and / or 18b, such that the acoustic path 34 in the region of path segments 381 to 384 runs perpendicular to the sound propagation directions 18a and / or 18b, or at least has a directional component perpendicular to the sound propagation directions 18a and / or 18b. The path segments can extend in different planes of the impedance matching body 12 between sides 14 and 16, for example, if the planes are considered to be parallel to sides 14 and / or 16.

[0049] Path sections 381, 382, ​​383, and 384 can each have an acoustically effective cross-section 421, 422, 423, and 424, respectively, which can be influenced by the size or extent of the cavity 32 in the region of the respective path section 381 to 384. For example, the acoustically effective cross-section 42 iof path section 38 i The acoustically effective cross-sections 421 to 424 may be determined or influenced by the distance between adjacent microstructures 221 and 222, 222 and 223, and / or between a microstructure 221 or 223 and its side 14 or 16, respectively. The acoustically effective cross-sections 421 to 424 may be the same or different from one another, whereby, for example, an acoustic cross-section decreasing along a sound transmission direction 18a or 18b may cause an increase in an acoustic sound characteristic impedance.

[0050] A reduction 441, 442, and / or 443 of the acoustic path 34 or the acoustically effective cross-section can be arranged between two potentially consecutive path segments 381 and 382, ​​382 and 383, and / or 383 and 384. Such a reduction can be achieved, for example, by a distance between the microstructures and boundary structures 461 and / or 462, such as sidewall structures. Alternatively, it is also possible to provide a reduction 44 between two adjacent microstructures 22, for example, between microstructures 221 and 222 to obtain a reduction 444. Microstructures 224 and / or 225 can be provided for this purpose, whereby other materials and / or dimensions and / or geometries can also be used, as long as these structures have a higher acoustic impedance than the cavity 32 in the region of the corresponding path segment.Although the additional arrangement of the microstructures 224 and 223 entails a corresponding manufacturing effort, it enables a precise adjustment of the acoustic characteristic impedance of the impedance matching device 50. In contrast, the tapers 441 to 443 can be manufactured easily, as they can result, for example, from a distance between the microstructures 221 to 223 and the boundary structures 461 and / or 462.

[0051] According to one embodiment, an acoustically effective cross-section can be 42 i at least one path section 38 i its axial extent, for example along the x-direction, can be variable. This can be achieved, for example, by varying the dimensions of at least one of the microstructures 221, 222 and / or 223 along the sound transmission direction 18a and / or 18b; alternatively or additionally, additional structures can also be incorporated along path segment 38. ibe provided. The acoustically effective cross-sections 42 i They can be set individually, in groups, or all at once. This means that the acoustically effective cross-section of two adjacent path sections can be different.

[0052] In other words, it shows Fig. 5. A wound structure in which the matching layer system consists of coiled or wound structures that increase the travel time of the sound wave. In Fig. Figure 5 shows the wound structures as a cross-section through a unit cell of a layered system applied to a sound transducer. The desired acoustic impedance profile can be generated by several intertwined channels. This allows the acoustic impedance to be influenced by the wave propagation time via the speed of sound until the wave arrives at the medium side of the layered system.

[0053] The previously described embodiments illustrate different configurations of the microstructures within the impedance matching body. As explained, each of these embodiments can provide a single-stage, multi-stage, or gradient-like acoustic impedance matching. The different embodiments can be combined in any way, allowing for the arrangement of differently shaped microstructures and / or grid structures in different planes perpendicular to and / or parallel to the sound propagation direction. This can be achieved, for example, in a single piece, such as by shaping the microstructures differently in different regions of the impedance matching body.Alternatively, a multi-piece arrangement can be used, for example by mechanically and / or acoustically coupling impedance matching elements according to various embodiments, each forming a layer of a multi-layered impedance matching element.

[0054] Different configurations allow the characteristic acoustic impedance to be continuous or discontinuous between the first side 14 and the second side 16 of the resulting impedance matching structure. An example of a continuous profile is a linear and / or exponential progression of the characteristic acoustic impedance along the sound propagation direction 18a and / or 18b.

[0055] Exemplary embodiments provide that the impedance matching device is designed such that the impedance matching element has different characteristic impedances on its different sides. One of the sides can, for example, be matched to the characteristic impedance of a MUT transducer, so that the characteristic impedance of the impedance matching element matches the characteristic impedance of the MUT transducer within a tolerance range of ±50%, ±25%, or ±10%. This means that the characteristic impedance values ​​are identical. An exemplary value for this is 1-35 MRayl. A range of 1-5 MRayl can be well suited for diaphragm transducers, which include MUT transducers. The range of 1-35 MRayl also includes ceramic and composite transducers, such as PZT-based transducer classes.The acoustic impedance on the other side can, if possible, match or at least approximate the acoustic impedance of a target medium, for example a fluid such as air.

[0056] Fig. Figure 6 shows a schematic block diagram of a transducer device 60 according to an exemplary embodiment. The transducer device 60 includes, for example, the impedance matching device 10. The transducer device 60 further includes a sound transducer element 48, which can be configured either to generate a sound wave based on a drive signal or alternatively or additionally to provide an electrical signal based on an incoming sound wave. This means that the transducer element 48 can be implemented as or include a sound actuator and / or sound sensor.

[0057] The impedance matching device 10 is coupled to the transducer element 48 at side 14, for example, by mechanically coupling the impedance matching device to the transducer element 48. For example, the impedance matching device 10 can be deposited on the transducer element 48, or vice versa. Although the transducer device 60 is described such that the transducer element 48 is acoustically coupled to side 14, the transducer element 48 can alternatively also be acoustically coupled to side 16. The other side, 16 or 14, can be configured to contact a medium into which a sound wave is to be emitted or from which a sound wave is to be received.Alternatively, another acoustically effective structure, for example another sound transducer element, can be acoustically coupled on the other side, so that impedance matching between two sound transducer elements can be carried out based on the impedance matching device 10.

[0058] Preferably, the acoustic coupling between the sound transducer element 48 and the side 14 has a continuous transition of the characteristic acoustic impedance, meaning that within the tolerance range of ±50%, ±25% or ±10%, the characteristic acoustic impedance of the sound transducer element 48 is in accordance with the characteristic acoustic impedance of the impedance matching device on the side 14.

[0059] The transducer element 48 can comprise a piezoelectric ceramic material and / or a composite material. In particular, the transducer element 48 can comprise a piezoelectric thin-film material, such as PVDF (polyvinylidene fluoride). According to one embodiment, the transducer element 48 comprises a micromachined ultrasonic transducer, for example a capacitive MUT (CMUT), a piezoelectric MUT (PMUT), or a magnetic MUT (MMUT).

[0060] Although the transducer device 60 is described such that the impedance matching device 10 is arranged, alternatively or additionally another and / or different impedance matching device may also be arranged, for example, the impedance matching device 10, 20, 30, 40a, 40b, 40c, 40d and / or 50. For example, impedance matching devices may be arranged which have a combination of different layers, each with at least one impedance matching device or impedance matching body, wherein, for example, an impedance matching device 40a, 40b, 40c, 40d may provide a layer of the common body with a sound characteristic impedance that is constant, at least on average.

[0061] In other words, the described adaptation structures can be integrated into single- and multi-channel, for example air-coupled, CMUT components and CMUT systems in one embodiment to increase the transducer range, sensitivity, and bandwidth. Such systems can be optimized as miniaturized sensors for distance and motion detection as well as imaging, and further enable, for example, gesture control in vehicle interiors (automotive), contactless control of household appliances (consumer), sensor applications in medical technology, and integration into mobile applications in service and industrial robots (industry).

[0062] Fig. Figure 7 shows a schematic block diagram of a system according to an exemplary embodiment, which includes, for example, the transducer device 60 and a control unit 52. The control unit 52 is configured to operate the sound transducer element 48, that is, to provide the sound transducer element 48 with a control signal 541 to excite the sound transducer element 48 to emit a sound transducer 561 and / or to receive a sound transducer signal 542 from the sound transducer element 48, which it provides based on an incoming sound wave 562.

[0063] The control unit 52 can be configured to operate the sound transducer element 48 in an ultrasonic frequency range, that is, in a frequency range of at least 20 kilohertz. For example, the control unit can be configured to operate the sound transducer element 48 in a frequency range of at least 20 kilohertz and at most 200 megahertz, at least 20 kilohertz and at most 150 megahertz, or at least 20 kilohertz and at most 100 megahertz.

[0064] Fig. Figure 8 shows a schematic flow diagram of a method 800 according to an embodiment for manufacturing an impedance matching device, for example the impedance matching device 10, 20, 30, 40a, 40b, 40c, 40d and / or 50.

[0065] Method 800 comprises a step 810. In step 810, an impedance matching body with a first and an opposing second side is provided. The impedance matching body is designed to match the acoustic impedance of a medium contacted on the first side to the acoustic impedance of a transducer contacted on the second side, such that the impedance matching body comprises microstructures that have a structural extent of at most 500 nanometers along at least one spatial direction.

[0066] For method 800, the impedance matching element can be manufactured, for example, by placing it directly on or attached to a sound transducer or by manufacturing it as a separate component.

[0067] The fabrication of the impedance matching body can include the provision of a transfer material. A positive or negative form of the microstructures can be formed in the transfer material. According to one embodiment, the transfer material comprises a curable polymer material, in particular a polymer material suitable for use in multiple-photon absorption lithography, for example, SU-8 and / or Ormocere. The creation of the positive or negative form can be achieved by subjecting the transfer material to at least two photons at a specific location, thereby causing a local change in the structural composition of the transfer material, i.e., curing or, alternatively, liquefaction of the polymer material. The multiple-photon absorption lithography can provide feature sizes of at most 500 nanometers, at most 300 nanometers, or at most 100 nanometers.

[0068] According to one embodiment, the transfer material comprises a metallic material in which, for example, the positive or negative form of the microstructures can be obtained by an ablation process using multiple photon absorption, in particular a laser ablation process. However, the transfer material is not limited to a metallic material but can also, according to further embodiments, comprise a different material in a solid or liquid state for the (laser) ablation process using multiple photon absorption and, for example, include a fluid, such as a polymerizable fluid or a fluid in a solid state, a semiconductor material, at least one organic compound, and / or a ceramic material.

[0069] Microstructures with different materials can be combined with each other, so that the use of a metal material, the use of a polymer material, the use of the fluid in solid or liquid state and / or the ceramic material in solid or liquid state can be combined arbitrarily, for example in different layers of the impedance matching body.

[0070] The resulting positive or negative mold can be further processed. For example, the manufacturing process can include coating the positive or negative mold. Alternatively or additionally, the positive or negative mold can be inverted. Inversion refers to a change in the material of the positive or negative mold. For example, the positive or negative mold can be coated, then the material can be removed, perhaps using a solvent or an etching process, and finally the resulting cavity can be filled with a suitable material.The small feature sizes achieved through multiple-photon lithography and / or laser ablation via multiple-photon absorption can be retained, enabling the production of such small feature sizes even in materials that cannot be processed with such precision using subtractive methods. Post-processing can further include casting the positive or negative mold. Casting can be understood as transferring the shape from the positive or negative mold into a corresponding new mold. Alternatively or additionally, the positive or negative mold can be enclosed, retaining, for example, the previously produced positive or negative mold as a core. (With reference to examples...) Fig. 3. For example, material 24 can be cured by a lithographic process and used as a positive mold, allowing for the filling of other materials. Alternatively or additionally, the impedance matching body 30 can be obtained by creating cavities into which material 24 is subsequently filled. This means that the production of the impedance matching body can involve the creation of microstructures in such a way that these are formed as tapered microstructures, which applies both to the areas containing material 24 and to the spaces between them.

[0071] According to one embodiment, the production of the impedance matching body can include creating at least one cavity located within the impedance matching body, which can alter the effective density of the impedance matching body. Creating a cavity can involve both curing to retain a material and removing a material, and describes, for example, the creation of different materials and / or densities within the impedance matching body in a spatial center to change the density of the impedance matching body in that spatial center.

[0072] As it is in connection with the Fig. 4a, Fig. 4b, Fig. 4c and Fig. As described in section 4d, the fabrication of the impedance matching body can include generating the microstructures as a lattice structure. The lattice structure can be formed from an impedance matching material of the impedance matching body and define cavities extending along the direction perpendicular to the sound transmission direction within the impedance matching body. The cavities can, for example, have a polygonal cross-section with three, four, five, six, seven, or a higher number of vertices and / or edges, with the structures being combinable with one another. The microstructures in the Fig. 4a, Fig. 4b, Fig. 4c and / or 4d can therefore be formed from cured polymer material and / or the metal material, but can also comprise a material that has been injected into a corresponding negative mold, whereby the transfer material for defining these structures may later be dissolved out or remain.

[0073] According to one embodiment, the manufacturing process comprises generating the microstructures such that the microstructures define an acoustic path between the sides of the impedance matching body, as is the case, for example, in the context of Fig. As described in section 5, a material of the microstructures may exhibit a higher acoustic impedance than the impedance matching element in a region of the acoustic path. Compared to a direct connection between the first and second sides, the acoustic path can provide a longer travel time for sound transmitted through it.

[0074] In other words, the approach of the present invention offers a particular advantage over known microstructures and methods for their fabrication in that it enables the creation of three-dimensional structures of virtually any shape and, above all, generous undercuts. According to one embodiment, the impedance matching body includes an undercut, meaning it comprises a shape with a section that would prevent its removal from a casting mold or impression mold. This is possible according to the described fabrication methods because arbitrary three-dimensional structures can be produced using ablation and / or lithography processes.

[0075] An exemplary manufacturing process is described in EP 1 084 454 B1. A polymerization process using multi-photon absorption can be employed, according to one embodiment of the described approach, to create microstructures with specific acoustic impedances or acoustic impedance profiles. The methods described therein allow the production of structure sizes of at most 500 nanometers and less, for example, at most 300 nanometers or at most 100 nanometers or less. The methods offer high flexibility in the design and fabrication of the microstructures for acoustic impedance matching.

[0076] The aforementioned properties offer the advantage of generating precise, exponential sound characteristics, thus ensuring ideal coupling between the ultrasonic transducer and the load medium. Furthermore, the high resolution (small structural dimensions) can be used to significantly reduce the characteristic acoustic impedance over short distances, making it suitable for media such as air. Diffraction effects and other attenuation effects, typically introduced by microstructures, can be reduced or even eliminated through targeted microstructure design. Another advantage of the high precision is the ability to create a very accurate layer system height, which strongly influences the transmission behavior.A further advantage is that intermediate and adhesive materials, which were previously required between individual impedance layers of different matching layers, can be dispensed with, although this does not preclude their use in the future. This eliminates their negative and unwanted influences on sound transmission and eliminates complex and labor-intensive deposition steps. The described methods are, in principle, applicable to any type of transducer. Advantages lie in the precision that can be achieved, particularly with miniaturized transducer elements and systems, thus contributing added value especially to MEMS-based transducers, sound sensors, and sound actuators.

[0077] Aspects of the embodiments described herein relate, among other things, to the following features: 1. System comprising a sound transducer with at least one channel and a sound characteristic impedance module for matching the acoustic impedance between a sound transducer and an ambient medium, characterized in that the sound characteristic impedance module has structural sizes below 500 nm. 2. System in which the typical structure size of the acoustic characteristic impedance modulus is less than or equal to 100 nm. 3. System, with a characteristic acoustic impedance module, characterized in that it has a homogeneous or inhomogeneous characteristic acoustic impedance profile. 4. System, with a sound characteristic impedance module, characterized in that it has a homogeneous sound characteristic impedance between the transducer and the ambient medium, preferably with characteristic values ​​of the sound characteristic impedance between that of the transducer and that of the ambient medium, preferably air. 5. System, with a sound characteristic impedance module, characterized in that the layer system as in 2 consists of several layers of constant sound characteristic impedance, wherein the sound characteristic impedance of the individual layers differs and preferably exhibits characteristic values ​​between the sound characteristic impedances of the sound transducer and the medium, preferably air. 6. System, with a sound characteristic impedance module, characterized in that the sound characteristic impedance module has a linear characteristic impedance profile, preferably with a continuous transition of the sound characteristic impedance between the transducer and the sound characteristic impedance module as well as between the sound characteristic impedance module and the load medium. 7. System, with a sound characteristic impedance module, characterized in that the sound characteristic impedance module has an exponential curve of the sound characteristic impedance, preferably with a continuous transition of the sound characteristic impedance between transducer and the sound characteristic impedance module as well as between the sound characteristic impedance module and the load medium. 8. System characterized in that the sound transducer is operated as a sound actuator. 9. System characterized in that the sound transducer is operated as a sound sensor. 10. System characterized in that the sound transducer is operated both as a sound actuator and as a sound sensor. 11. System, characterized in that the sound transducer operates in the ultrasonic frequency range, preferably in the range between 20 kHz and 100 MHz. 12. System characterized in that the sound transducer is based on piezoelectric ceramics and composite materials, for example PZT. 13. System characterized in that the sound transducer is based on piezoelectric materials applied using thin-film processes, for example PVDF. 14. System, characterized in that the sound transducer is realized as a micromachined sound transducer (MUT); preferably with capacitive (CMUT), piezoelectric (PMUT) and magnetic operating principles (MMUT). 15. Method for producing a sound characteristic impedance module for matching the acoustic impedance between a sound transducer and an ambient medium, characterized in that the sound characteristic impedance module has structure sizes below 500 nm. 16. Method in which the typical structure size of the acoustic characteristic impedance modulus is less than or equal to 100 nm. 17. Method characterized in that the adaptation is carried out by generating microcavities and thereby the acoustic characteristic impedance modulus is changed in its effective density, effective speed of sound and thus acoustic characteristic impedance by cavities, channels or inclusions. 18. Method characterized in that the adaptation is carried out by generating tapered structures and thereby divides the acoustic characteristic impedance modulus into several conically tapered volumes and consequently changes its effective density, effective speed of sound and thus acoustic characteristic impedance. 19. Method, characterized in that the matching is carried out by generating microgrids and the acoustic characteristic impedance modulus consists of scaffold-like gratings with variable scaffold elements, preferably hexagons, hexagons / triangles, triangulars and diamonds. 20. Method characterized in that the adaptation is carried out by generating wound structures and the sound characteristic impedance modulus consists of wound or coiled structures which increase the transit time of the sound wave. 21. Method using the multiple-photon absorption lithography method for generating the acoustic characteristic impedance modulus, characterized in that a transfer medium changes its structural composition under the targeted action of at least two photons and generates a mechanically stable structure compared to the environment. 22. A process in which the transfer medium consists of liquid and / or solid polymers, metals, gases, ceramics and / or combinations of these materials. 23. A method in which the structures produced are post-processed, preferably by coating, inversion, casting and inclusions.

[0078] Although some aspects have been described in connection with a device, it is understood that these aspects also constitute a description of the corresponding process, so that a block or component of a device can also be understood as a corresponding process step or as a feature of a process step. Similarly, aspects described in connection with or as a process step also constitute a description of a corresponding block, detail, or feature of a corresponding device.

[0079] The embodiments described above merely illustrate the principles of the present invention. It is understood that modifications and variations of the arrangements and details described herein will be obvious to other people skilled in the art. Therefore, it is intended that the invention be limited only by the scope of protection set forth in the following claims and not by the specific details presented herein by way of description and explanation of the embodiments. [1] S. Saffar and A. Abdullah, "Determination of acoustic impedances of multi matching layers for narrowband ultrasonic airborne transducers at frequencies <2.5 MHz - Application of a genetic algorithm," U / trasonics, vol. 52, no. 1, pp. 169-185, 2012. [2] T. R. GURURAJA, WALTER A. SCHULZE, LESLIE E. CROSS, and AND ROBERT E. NEWNHAM, „Piezoelectric Composite Materials for Ultrasonic Transducer Applications. Part ii: Evaluation of Ultrasonic Medical Applications,“ [3] Ergun et a / ., „Capacitive Micromachined Ultrasonic Transducers: Theory and Technology,“ J. Aerosp. Eng, vol. 16, no. 2, 2003. [4] R. Lerch, G. M. Sessler, and D. Wolf, Technische Akustik: Grundlagen und Anwendungen. Berlin: Springer, 2009. [5] O. Krauß, R. Gerlach, and J. Fricke, „Experimental and theoretical investigations of SiOZ-aerogel matched piezo-transducers,“ Ultrasonics, vol. 32, no. 3, pp. 217-222, 1994. [6] T. Yano, M. Tone, and A. Fukumoto, „Range Finding and Surface Characterization Using High-Frequency Air Transducers,“ IEEE Trans. Ultrason., Ferroe / ect., Freq. Contr., vol. 34, no. 2, pp. 232-236, 1987. [7] T. Manh, A.-T. T. Nguyen, T. F. Johansen, and L. Hoff, „Microfabrication of Stacks of acoustic matching layers for 15 MHz Ultrasonic transducers,“ (eng), U / trasonics, vol. 54, no. 2, pp. 614-620, 2014. [8] M. I. Haller and B. T. Khuri-Yakub, „Micromachined Ultrasonic Materials”, Ultrasonics Symposium, 1991. [9] Z. Li et a / ., „Broadband gradient impedance matching using an acoustic metamaterial for Ultrasonic transducers,“ (eng), Scientific reports, vol. 7, p. 42863, 2017.

[10] G.-H. Feng and W.-F. Liu, „A spherically-shaped PZT thin film Ultrasonic transducer with an acoustic impedance gradient matching layer based on a micromachined periodically structured flexible substrate,“ Sensors (Basel, Switzerland), vol. 13, no. 10, pp. 13543-13559, 2013.

Claims

[1] Impedance matching device for matching a sound characteristic impedance with: an impedance matching body (12) with a first side (14) and an opposite second side (16), wherein the impedance matching device is configured to match a sound characteristic impedance of a medium contacted on the second side (16) to a sound characteristic impedance of a transducer (48) contacted on the first side (14); wherein the impedance matching body (12) comprises microstructures (22) which have a structural extent (26) of at most 500 nm along at least one spatial direction; the microstructures (22) form a lattice structure extending along a direction perpendicular to a sound transmission direction (18a, 18b) between the first side (14) and the second side (16) of the impedance matching body (12) in the impedance matching body (12); or wherein the microstructures (22) define an acoustic path (34) between the first side (14) and the second side (16), wherein a material of the microstructures (22) has a higher acoustic characteristic impedance than the impedance matching body (12) in a region of the acoustic path (34), wherein the acoustic path (34) provides a time extension for sound transmitted through the acoustic path (34) compared to a direct connection between the first side (14) and the second side (16). [2] Impedance matching device according to claim 1, wherein the microstructures (22) are formed comprising an impedance matching material comprising a metal material, a semiconductor material, an organic compound, a ceramic material or comprising a polymer material. [3] Impedance matching device according to claim 1 or 2, wherein the microstructures (22) comprising a first impedance matching material are formed, wherein a second impedance matching material (24) is arranged in intermediate regions between the microstructures (22). [4] Impedance matching device according to one of the preceding claims, wherein the structural extent (26) of at least one microstructure (22) is perpendicular to an axial extension direction of the microstructures (22). [5] Impedance matching device according to one of the preceding claims, wherein the microstructures (22) define cavities, wherein an effective material density of an impedance matching material of the impedance matching body (12) between the first side (14) and the second side (16) is monotonically variable through the cavities, and effects the matching of the acoustic characteristic impedance. [6] Impedance matching device according to claim 5, wherein the microstructures (22) define branched microchannels, the number of which is monotonically variable between the first and second side (16). [7] Impedance matching device according to one of the preceding claims, wherein the microstructures (22) are formed as structures tapering towards the first (14) or towards the second side (16), and have the structure extension (26) at least in a region of minimal extent (28). [8] Impedance matching device according to claim 7, wherein the microstructures (22) taper conically. [9] Impedance matching device according to one of the preceding claims, wherein the microstructures (22) form a lattice structure extending along a direction perpendicular to a sound transmission direction (18a, 18b) between the first side (14) and the second side (16) of the impedance matching body (12) in the impedance matching body (12), wherein the lattice structure is formed from an impedance matching material of the impedance matching body (12) and defines cavities extending along the direction (x, y) perpendicular to a sound transmission direction (18a, 18b) in the impedance matching body (12), wherein the cavities have a polygonal cross-section. [10] Impedance matching device according to one of the preceding claims, wherein the microstructures (22) define an acoustic path (34) between the first side (14) and the second side (16), wherein a material of the microstructures (22) has a higher acoustic characteristic impedance than the impedance matching body (12) in a region of the acoustic path (34), wherein the acoustic path (34) provides a time extension for sound transmitted through the acoustic path (34) compared with a direct connection between the first side (14) and the second side (16);and the acoustic path (34) is formed as a folded structure with a plurality of path segments (38), wherein the plurality of path segments (38) extend perpendicular to a sound transmission direction (18a, 18b) between the first side (14) and the second side (16) in the impedance matching body (12) in different planes perpendicular to the sound transmission direction (18a, 18b). [11] Impedance matching device according to claim 10, in which a reduction (441) of the acoustically effective cross-section is arranged between a first path section (381) of the plurality of path sections, which has a first acoustically effective cross-section (421), and a second path section (382) of the plurality of path sections, which has a second acoustically effective cross-section (422). [12] Impedance matching device according to claim 10 or 11, in which an acoustically effective cross-section (44) of at least one path segment (38) of the plurality of path segments is variable over its axial extent. [13] Impedance matching device according to one of claims 10 to 12, in which an acoustically effective cross-section (421) of a first path section (381) of the plurality of path sections and an acoustically effective cross-section (422) of an adjacent second path section (422) of the plurality of path sections are different from each other. [14] Impedance matching device according to one of the preceding claims, wherein the microstructures (22) are formed in one piece at least within a layer of the impedance matching body (12). [15] Impedance matching device according to one of the preceding claims, wherein the structural extent (26) is at most 100 nm. [16] Impedance matching device according to one of the preceding claims, wherein the sound characteristic impedance between the first side (14) and the second side (16) is continuous or discontinuous. [17] Impedance matching device according to claim 16, wherein the characteristic acoustic impedance is exponential. [18] Impedance matching device according to one of the preceding claims, wherein the impedance matching body (12) has a first acoustic characteristic impedance value on the first side (14) and a second acoustic characteristic impedance value on the second side (16), wherein either the first acoustic characteristic impedance value or the second acoustic characteristic impedance value corresponds to an acoustic characteristic impedance value of a MUT transducer within a tolerance range of ±50%. [19] Impedance matching device according to claim 18, wherein the target medium is air. [20] Impedance matching device according to one of the preceding claims, wherein the impedance matching body (12) is formed in multiple layers, comprising at least a first layer with a first layer characteristic impedance and a second layer with a second layer characteristic impedance which is different from the first layer characteristic impedance. [21] Impedance matching device according to one of the preceding claims, wherein the impedance matching body (12) has an undercut [22] Converter device with: an impedance matching device according to one of the preceding claims; and a sound transducer element (48) which is acoustically coupled to either the first side (14) or the second side (16) of the impedance matching body (12) by means of an acoustic coupling. [23] Transducer device according to claim 22, wherein the acoustic coupling has a continuous transition of the sound characteristic impedance. [24] Transducer device according to claim 22 or 23, wherein the sound transducer element (48) comprises a sound actuator and / or a sound sensor. [25] Transducer device according to one of claims 22 to 24, wherein the sound transducer element (48) comprises a piezoelectric ceramic material and / or a composite material. [26] Transducer device according to one of claims 22 to 25, wherein the sound transducer element (48) comprises a piezoelectric thin-film material, in particular a polyvinylidene fluoride material. [27] Transducer device according to one of claims 22 to 26, wherein the sound transducer element (48) comprises a MUT sound transducer. [28] System with: a converter device according to any one of claims 22 to 27; and a control unit (52) designed to operate the sound transducer element (48). [29] System according to claim 28, wherein the control unit (52) is configured to operate the sound transducer element (48) in an ultrasonic frequency range. [30] Method (800) for manufacturing an impedance matching device comprising the following step: Providing (810) an impedance matching body (12) with a first and an opposite second side (16) configured to match a sound characteristic impedance of a medium contacted at the second side (16) to a sound characteristic impedance of a transducer (48) contacted at the first side (14); so that the impedance matching body (12) comprises microstructures (22) which have a structural extent (26) of at most 500 nm along at least one spatial direction; wherein the provision (810) of the impedance matching body (12) comprises a manufacture thereof, wherein the manufacture comprises generating the microstructures (22) as a lattice structure, such that the lattice structure is formed from an impedance matching material of the impedance matching body (12) and defines cavities extending along the direction perpendicular to a sound transmission direction (18a, 18b) in the impedance matching body (12), wherein the cavities have a polygonal cross-section; or wherein the provision (810) of the impedance matching body (12) comprises a manufacture thereof, wherein the manufacture comprises a generation of the microstructures (22) which is carried out such that the microstructures (22) define an acoustic path between the first side (14) and the second side (16), such that a material of the microstructures (22) has a higher acoustic characteristic impedance than the impedance matching body (12) in a region of the acoustic path, such that the acoustic path provides a time extension for sound transmitted through the acoustic path compared with a direct connection between the first side (14) and the second side (16). [31] Method according to claim 30, wherein the provision (810) of the impedance matching body (12) comprises a manufacture thereof by the following steps: Providing transfer material; Generating a positive or negative form of the microstructures (22) in the transfer material. [32] Method according to claim 31, wherein the transfer material is a curable transfer material and wherein the generation of the positive or negative form of the microstructures (22) in the curable transfer material is carried out by curing the same by performing multiple photon absorption lithography, which causes a local change in the structural composition of the curable transfer material. [33] Method according to claim 31 or 32, wherein the transfer material is in a solid or liquid state and comprises at least one of a metal material, a semiconductor material, an organic compound, a ceramic material, a polymer material and a fluid. [34] Method according to any one of claims 31 to 33, wherein the provision (810) of the impedance matching body (12) comprises manufacturing the same by the following steps: Providing transfer material; Generating a positive or negative form of the microstructures (22) in the metal material by laser ablation through multiple photon absorption of the same. [35] Method according to any one of claims 31 to 34, wherein the provision (810) of the impedance matching body (12) comprises manufacturing the same by at least one of the following steps: Coating the positive or negative mold; and / or Inverting the positive or negative form; and / or Casting the positive or negative mold; and / or Including the positive form or negative form. [36] Method according to any one of claims 31 to 35, wherein the provision (810) of the impedance matching body (12) comprises manufacturing the same, wherein the manufacturing comprises generating at least one cavity in the impedance matching body (12) for changing an effective density of the impedance matching body (12). [37] Method according to any one of claims 31 to 36, wherein the provision (810) of the impedance matching body (12) comprises manufacturing the same, wherein the manufacturing comprises generating the microstructures (22) such that they are formed as tapered microstructures (22).

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