Ultrasound transducer assembly, probe, system and method of manufacture

Abstract

The present application provides an ultrasonic transducer assembly for ultrasound / photoacoustic dual-mode imaging of an endoscope, comprising an ultrasonic transducer and a micro-lens integrated in the ultrasonic transducer for collimating or focusing a light beam, wherein the micro-lens is integrated in the ultrasonic transducer in a manner of being accommodated in an orifice of the ultrasonic transducer. A probe / catheter comprising the ultrasonic transducer assembly, a system comprising the probe / catheter and a method of manufacturing the ultrasonic transducer assembly are also provided. The present application solves the problems of light supply and device size (rigidity length, diameter) by using a light-cured glue and a mold to manufacture the micro-lens in the ultrasonic transducer and adopting coaxial arrangement of the devices, and simplifies the manufacturing process of an intravascular photoacoustic probe / catheter.

Description

[0001] This application is a divisional application of the invention patent application filed on October 29, 2020, with application number 202011176786.4 and the invention title "Ultrasonic transducer assembly, probe, system and manufacturing method". Technical Field

[0002] This invention relates generally to intravascular imaging technology, particularly to intravascular photoacoustic (IVPA) endoscopy and / or intravascular photoacoustic / ultrasound dual-mode imaging, and more particularly to an ultrasound transducer assembly for ultrasound / photoacoustic dual-mode imaging of an endoscope, an ultrasound-photoacoustic probe including the assembly, an endoscopy system including the ultrasound-photoacoustic probe, and a method of manufacturing the ultrasound transducer assembly. Background Technology

[0003] Vulnerable plaque rupture is a major cause of acute cardiovascular events. Early diagnosis and early warning of vulnerable plaques are key technologies for reducing cardiovascular disease mortality. Currently, there are three main intravascular imaging techniques: intravascular ultrasound, intravascular optical coherence tomography (OCT), and intravascular infrared spectroscopy. Intravascular ultrasound can distinguish the structure of different membrane layers of the vessel wall, but because the acoustic impedance of various soft tissue components is relatively similar, ultrasound imaging cannot accurately determine plaque composition. Intravascular optical coherence tomography has a high resolution of 10-20 μm and can accurately detect thin fibrous caps on plaques; however, its imaging depth is typically only ~1 mm, and even smaller on the plaque itself, making it impossible to assess the overall plaque structure. Intravascular infrared spectroscopy can obtain information on tissue composition, but it lacks depth information and cannot determine the physical location of the components. Therefore, the development of a high-resolution intravascular imaging system with large imaging depth, capable of obtaining morphological and compositional information, has become an urgent clinical need.

[0004] Intravascular photoacoustic imaging (ACE) is an intravascular imaging technique for atherosclerosis, demonstrating great potential in acquiring information on plaque tissue composition and inflammatory physiological functions. The basic principle of ACE is to obtain information about tissue light absorption by detecting the ultrasound signal (photoacoustic signal) generated by the transient thermoelastic effect after biological tissue absorbs a pulsed laser. The contrast of ACE originates from light absorption, while the resolution primarily comes from the ultrasound signal. This fundamentally overcomes the limitations of high-resolution purely optical imaging methods such as OCT and confocal microscopy, which suffer from low penetration depth due to light scattering. Based on the selective light absorption of different molecules and photoacoustic spectroscopy, highly sensitive detection of plaque chemical components can be achieved. ACE itself can obtain depth information; combined with ultrasound imaging, it can distinguish the structure of different membrane layers of the blood vessel wall and the distribution of plaques, providing strong evidence for the identification and assessment of vulnerable plaques.

[0005] Intravascular photoacoustic (IVPA) endoscopic catheters / probes are key tools for photoacoustic imaging of plaques and vascular nutrient vessels, and they are mainly designed in the following two types:

[0006] 1. Optical components are placed next to the ultrasonic transducer (UT). For example, the methods used in Chinese patents: 201410829245.5, 201710846057.7, and 201810121955.0. The optical components, such as optical fibers, gradient index (GRIN) lenses, and mirrors, are all positioned in a straight line, while the UT is positioned to the side or top of the optical components.

[0007] In endoscopic examinations, higher light flux results in higher photoacoustic signals. To provide better imaging, most catheters use GRIN lenses to focus the light; these lenses are typically 0.5 mm in diameter. In this way, the GRIN lens focuses the light in the (laser) fiber into a spot, thereby increasing the light flux, i.e., the light energy or light energy density per unit area. However, this limits the overlapping area of ​​light and sound, within which photoacoustic signals can only be detected. Simultaneously, the multiple optical elements result in a relatively long, rigid catheter length (>10 mm), making it difficult to pass through small arteries for intravascular endoscopy.

[0008] 2. The optical element is located at the center of the ring UT, see Chinese Patent 201710364571.7 and US Patent: US10182791B2.

[0009] This method expands the detection area, but the use of a GRIN lens results in a larger ultrasound transducer, leading to a larger catheter (diameter > 1 mm). The diameter of the IVPA catheter should be limited to within 1 mm to reduce difficulty in passing through the artery. Most importantly, this design cannot be used with endovascular endoscopy because the large central orifice (corresponding to the GRIN lens) degrades the performance of UT.

[0010] There is a need in this field to address the problems existing in the prior art – especially considering that in the case of ultrasound-photoacoustic dual-mode imaging, providing light without limiting the detection area and that the detector assembly / probe size may be too large for intravascular endoscopy. Summary of the Invention

[0011] This application specifically addresses the issues of light supply and device size (rigid length, diameter) by using a photocurable adhesive and a mold to manufacture micro-adhesive lenses located in an ultrasonic transducer and by employing a coaxial arrangement of the devices, thereby simplifying the manufacturing process of IVPA probes / conduits.

[0012] According to a first aspect of this application, an ultrasonic transducer assembly for ultrasonic / photoacoustic dual-mode imaging of an endoscope is provided, comprising an ultrasonic transducer and a microgel lens integrated in the ultrasonic transducer, the microgel lens being used for collimating or focusing a light beam, wherein the microgel lens is integrated in the ultrasonic transducer in such a way as to be accommodated in an aperture of the ultrasonic transducer.

[0013] In the ultrasonic transducer assembly according to the first aspect of this application, preferably, the micro-adhesive lens is a photocurable micro-adhesive lens that is cured in the orifice of the ultrasonic transducer using a photocurable adhesive.

[0014] In the ultrasonic transducer assembly according to the first aspect of this application, preferably, the photocurable adhesive is a fast-drying adhesive with high light transmittance.

[0015] In the ultrasonic transducer assembly according to the first aspect of this application, preferably, the photocurable adhesive is an ultraviolet-curable adhesive, and the photocurable micro-adhesive lens is an ultraviolet-curable micro-adhesive lens.

[0016] In the ultrasonic transducer assembly according to the first aspect of this application, preferably, the ultrasonic transducer is a ring-shaped ultrasonic transducer, comprising a matching layer, a piezoelectric layer, and a backing layer.

[0017] In the ultrasonic transducer assembly according to the first aspect of this application, preferably, the refractive index of the photocurable microgel lens is between 1.3 and 1.6.

[0018] In the ultrasonic transducer assembly according to the first aspect of this application, preferably, the diameter of the aperture and therefore the microgel lens is less than 200 μm.

[0019] According to a second aspect of this application, an ultrasonic-photoacoustic probe is provided, comprising an ultrasonic transducer assembly according to the first aspect, and further comprising a housing, a reflector, an optical fiber, a coil, and a wire, wherein the reflector, the ultrasonic transducer assembly, and the optical fiber are sequentially and coaxially disposed within the housing, the coil is used to transmit torque and is adapted to be inserted into the housing to induce a scanning action of the ultrasonic transducer assembly, the wire is connected to the ultrasonic transducer to induce ultrasound, and the optical fiber is optically coupled to the microgel lens.

[0020] In the ultrasonic-photoacoustic probe according to the second aspect of this application, preferably, the wire is connected to the ultrasonic transducer via silver paste.

[0021] In the ultrasonic-photoacoustic probe according to the second aspect of this application, preferably, the length of the housing is less than 3 mm and the diameter is less than 1 mm.

[0022] In the ultrasound-photoacoustic probe according to the second aspect of this application, preferably, the ultrasound-photoacoustic probe is used for ultrasound / photoacoustic dual-mode imaging of endovascular endoscopy.

[0023] According to a third aspect of this application, an endoscopic examination system is provided that includes an ultrasonic transducer assembly according to the first aspect or an ultrasonic-photoacoustic probe according to the second aspect.

[0024] According to a fourth aspect of this application, a method for manufacturing an ultrasonic transducer assembly according to the first aspect is provided, comprising the following steps:

[0025] A mold is provided, wherein the mold is provided with a concave smooth surface of predetermined curvature;

[0026] An ultrasonic transducer is provided, and an orifice corresponding to the smooth curved surface is machined in the ultrasonic transducer;

[0027] An ultrasonic transducer is placed on the mold, wherein the axis of the orifice of the ultrasonic transducer is aligned with the axis of the smooth curved surface;

[0028] A photocurable adhesive is introduced into the orifice of the ultrasonic transducer and fills the space between the sidewall of the orifice and the smooth curved surface; and

[0029] The photocurable adhesive is photocured to form a micro-adhesive lens integrated into the orifice of the ultrasonic transducer, wherein the curvature of the micro-adhesive lens is defined by a predetermined curvature of the smooth surface.

[0030] In the method according to the fourth aspect of this application, preferably, the mold is a metal mold, and a smooth surface with the predetermined curvature is formed in the mold by micromachining of a computer numerical control machine.

[0031] In the method according to the fourth aspect of this application, preferably, machining an orifice corresponding to the smooth surface in the ultrasonic transducer includes machining an orifice corresponding to the smooth surface at the center of the ultrasonic transducer by laser micromachining.

[0032] In the method according to the fourth aspect of this application, preferably, the ultrasonic transducer is an annular ultrasonic transducer, comprising a matching layer, a piezoelectric layer and a backing layer, and wherein placing the ultrasonic transducer on the mold comprises attaching the matching layer to a surface of the mold having the smooth curved surface.

[0033] In the method according to the fourth aspect of this application, preferably, the refractive index of the photocurable microgel lens is between 1.3 and 1.6.

[0034] In the method according to the fourth aspect of this application, preferably, the diameter of the orifice is less than 200 μm.

[0035] In the method according to the fourth aspect of this application, preferably, the photocurable adhesive is a fast-drying adhesive with high light transmittance.

[0036] In the method according to the fourth aspect of this application, preferably, the photocurable adhesive is an ultraviolet-curable adhesive, and the photocurable micro-adhesive lens is an ultraviolet-curable micro-adhesive lens.

[0037] According to this application, UV-curable adhesives, especially UV-curable adhesives, are used to form UV-curable microlenses, which are then used in the coaxial design of IVPA probes / catheters for focusing or collimating light. This allows for focusing or collimating light within a very small space, with the microcatheter / probe having a diameter of less than 1 mm and a length of less than 3 mm. Furthermore, the catheter / probe with the microlens has a simple structure and short rigid length, allowing for safer passage through blood vessels for intravascular ultrasound-photoacoustic / dual-mode imaging or endoscopy. Additionally, the coaxial design provides a large detection area (ultrasound-photoacoustic overlap region). Moreover, the method for manufacturing the ultrasound transducer assembly proposed in this application is simple and highly customizable, allowing for the integration of microlenses with different curvatures, refractive indices, and other properties into the ultrasound transducer assembly while keeping other components unchanged, according to different needs.

[0038] The present application will be further described below with reference to the accompanying drawings. Attached Figure Description

[0039] The accompanying drawings—in which like reference numerals denote like or similarly functional elements—contain figures of certain embodiments to further illustrate and clarify the various aspects, advantages, and features disclosed herein. It will be understood that these drawings depict only certain embodiments of the invention and are not intended to limit its scope. Those skilled in the art will understand that the elements in the figures are shown for simplicity and clarity and are not necessarily drawn to scale, wherein:

[0040] Figure 1 An ultrasonic-photoacoustic probe including an ultrasonic transducer assembly is shown according to an embodiment of the present invention.

[0041] Figure 2 An ultrasonic transducer according to an embodiment of the present invention is shown.

[0042] Figure 3 A flowchart illustrating the manufacture of an ultrasonic transducer assembly according to an embodiment of the present invention is shown.

[0043] Figure 4 An example application of an ultrasonic transducer assembly according to an embodiment of the present invention is shown. Detailed Implementation

[0044] As described above, this application specifically solves the problems of light supply and device size (rigid length, diameter) by using a photocurable adhesive and a mold to manufacture a micro-adhesive lens located in an ultrasonic transducer and by employing a coaxial arrangement of the device, thus simplifying the manufacturing process of the IVPA probe / catheter. According to this application, a UV-curable adhesive micro-adhesive lens is formed using a photocurable adhesive, especially a UV-curable adhesive, and used in the coaxial design of the IVPA probe / catheter for focusing or collimating light. This allows for focusing or collimating light within a very small space, enabling the microcatheter / probe diameter to be less than 1 mm and the front rigid tube length to be less than 3 mm. Furthermore, the catheter / probe with the micro-adhesive lens has a simple structure and short rigid length, allowing for safer passage through blood vessels for intravascular ultrasound-photoacoustic / dual-mode imaging or endoscopy. Additionally, the coaxial design allows for a large detection area (ultrasound-photoacoustic overlap area). Furthermore, the method for manufacturing ultrasonic transducer components proposed in this application is simple in process and has strong customization capabilities. It can integrate micro-adhesive lenses with different curvatures, refractive indices and other properties into ultrasonic transducer components according to different needs while keeping other components unchanged.

[0045] First refer to Figure 1 This illustration shows an ultrasound-photoacoustic probe / catheter 100 including an ultrasound transducer assembly according to an embodiment of the present invention (the probe and catheter may be used interchangeably herein). The probe / catheter 100 is particularly suitable for intravascular ultrasound-photoacoustic dual-mode imaging.

[0046] The conduit 100 includes a reflector 110, a ring-type ultrasound transducer (UT) 120, a microgel lens 130 that receives, houses, or is disposed within the ring-type ultrasound transducer 120, a housing 140, a coil 150 (e.g., a torsion coil), a wire 170, and an optical fiber 180. The positive and negative terminals of the wire 170 are connected to the ultrasound transducer, for example, via silver paste 160, or can be connected to the ultrasound transducer in any manner known in the art to, for example, apply voltage / current to the ultrasound transducer to induce ultrasound (e.g., a pulse). The reflector 110 is positioned at one end (the distal end) of the housing 140 to reflect a light beam (from an optical fiber optically coupled to the microgel lens 130) emitted (collimated or focused). Specifically, the ultrasonic transducer assembly includes an ultrasonic transducer 120 and a microgel lens 130 integrated within the ultrasonic transducer 120. The microgel lens 130 is used to collimate or focus the beam, and is integrated into the ultrasonic transducer 120 in such a way that it is received within the aperture of the ultrasonic transducer 120. The length of the housing (or front-end rigid tube) 140 can be limited to within 3 mm, which is much shorter than the length of prior art. As shown, the ultrasonic transducer 120 with the embedded microgel lens 130 is coaxially arranged with other components such as the reflector 110, optical fiber, and coil, which allows for a large detection area. Specifically, the microgel lens 130 is a photocurable microgel lens that is cured in the aperture of the ultrasonic transducer 120 using a photocurable adhesive. More specifically, the photocurable adhesive is a UV-curable adhesive, and the photocurable microgel lens is a UV-curable microgel lens. Rotation and / or translation of the probe can be induced by the coil 150 for imaging scanning.

[0047] Regarding UV-curable adhesives, Chinese patent application No. 201410464946.3 discloses a formulation and properties of a liquid optical transparent adhesive, using epoxy-terminated polysiloxane as the main component, and applying it to the bonding of transparent optical components via UV curing. Its disclosed refractive index is around 1.53. Chinese invention patents with application numbers 201510341749.7, 201410300451.7, and 201310328818.1 disclose optical adhesives with refractive indices generally between 1.50 and 1.53. Chinese patent application No. 200810171323.1 discloses a high-refractive-index UV-curable coating adhesive for optical fiber coating, with a refractive index between 1.54 and 1.556. Furthermore, CN105802517A discloses UV-curable adhesives with refractive indices increased to greater than 1.58, and even reaching 1.60 or higher. Overall, this invention can utilize fast-drying adhesives with high light transmittance, especially UV-curable fast-drying adhesives. Embedding / setting micro-adhesive lenses in ultrasonic transducers using the method disclosed in this application simplifies manufacturing, provides customization capabilities, reduces component size without compromising ultrasonic transducer performance (because only tiny holes or openings are formed therein), and allows for coaxial configuration with other components (including optical components), achieving a large detection / probe range.

[0048] In this invention, a ring-shaped ultrasonic transducer is preferred, which refers to an ultrasonic transducer having a circular (micro)hole or aperture for receiving or accommodating a circular component. Specifically, the ring-shaped ultrasonic transducer does not necessarily have a circular / annular outer contour (discussed below). Figure 2-4 The diagram illustrates a square / cuboidal annular ultrasonic transducer, provided that the transducer has a circular aperture or opening for receiving or accommodating circular components (particularly lenses, more particularly microgel lenses, and even more particularly, microgel lenses made, for example, by curing adhesives, especially by UV curing of UV adhesives). In a preferred embodiment of the invention, the diameter of the aperture and thus the embedded microgel lens is less than 200 μm. The small size of the aperture and microgel lens, on the one hand, enables miniaturization of the entire device, facilitating its application in narrow blood vessels; on the other hand, the small / micro-aperture has minimal impact on the ultrasonic transducer.

[0049] In one embodiment, see Figure 2 The annular ultrasonic transducer 120 includes three layers: a matching layer 121, a piezoelectric layer 122, and a backing layer 133 (e.g., ...). Figure 2(As shown). Matching layer 121 is a layer that contacts / attaches to the mold during the manufacturing process of the ultrasonic transducer assembly. Piezoelectric layer 122 is a layer that generates ultrasound for ultrasonic or ultrasound-photoacoustic dual-mode imaging by performing piezoelectric action under applied voltage / current. Backing layer 133 forms the backing of the device for absorbing the rearward emitted ultrasonic signal. A micro-hole or micro-orifice is formed at the center of the ultrasonic transducer 120 using laser micromachining technology. Matching layer 121 faces mirror 110. A micro-adhesive lens is placed at the center of the ultrasonic transducer (within the central micro-hole or micro-orifice) using UV-curable adhesive for light focusing or collimation. An uncoated optical fiber is located at the center of the housing, aligned with the axis of the micro-adhesive lens. A signal (ultrasonic signal, e.g., ultrasonic pulse) is converted from the ultrasonic transducer by wires; specifically, the positive terminal is connected to the backing layer of the ultrasonic transducer with silver paste 160, and the negative terminal is connected to the matching layer of the ultrasonic transducer with silver paste 160. A coil (e.g., a torsion coil) is used to transmit torque for imaging scanning, and its end is adapted to be inserted into a housing.

[0050] The following is for reference. Figure 3 The document illustrates a flowchart of manufacturing an ultrasonic transducer assembly according to an embodiment of the present invention. The manufacturing method includes the following steps: providing a mold, wherein the mold has a concave smooth surface with a predetermined curvature; providing an ultrasonic transducer and machining an orifice in the ultrasonic transducer corresponding to the smooth surface; placing the ultrasonic transducer on the mold, wherein the axis of the orifice of the ultrasonic transducer is aligned with the axis of the smooth surface; introducing a photocurable adhesive into the orifice of the ultrasonic transducer and filling the space between the sidewall of the orifice and the smooth surface; and performing photocuring of the photocurable adhesive to form a micro-adhesive lens integrated into the orifice of the ultrasonic transducer, wherein the curvature of the micro-adhesive lens is defined by the predetermined curvature of the smooth surface.

[0051] Light emitted by a laser (not shown) is easily scattered. Traditionally, glass lenses or gradient-index lenses are used to focus or collimate the light; however, they are too large to fit into the micro-aperture (diameter less than 200 μm) of an ultrasound transducer suitable for endoscopic procedures. In this paper, the applicant proposes to combine a mold with a UV-curable adhesive to form a microlens. Generally, the UV-curable adhesive used has a refractive index between 1.3 and 1.6, similar to glass. The curvature of the microlens can be set using the mold. The curvature can be obtained through simulation using optical software or calculated optically under required constraints, or it can be specified.

[0052] Figure 3(a) shows a mold with a designed curved surface (concave surface) for forming a gel lens. The mold is made of metal with a smooth surface and is machined by a standard CNC machine tool. The mold can be designed in different shapes (square, rectangular, circular, etc.) with different surface curvatures. A ring-shaped UT is placed on the mold, and its mating layer adheres to the mold. Figure 3 (b) The micro-orifice axis of the ultrasonic transducer is aligned with the curved surface axis of the mold. UV adhesive is used to fill the gaps between the micro-orifices and the curved space. An adhesive lens is formed under UV irradiation. Figure 3 (b) It is readily understood that the mold and the concave surface of the mold can be processed using any technique understood by a person skilled in the art to give it a curvature and size derived from simulation or calculation, the curvature and size of which define or correspond to or are equal to the curvature and size of the formed microlens. Furthermore, the type and specific composition of the photocurable adhesive used (especially UV-curable adhesives with high light transmittance) can be selected as needed to obtain the desired refractive index and other properties. Some of the applications / patents mentioned above provide examples of photocurable adhesives, and those skilled in the art can readily understand these and other curing adhesives, as well as their curing conditions and processes; therefore, the applicant will not elaborate further here.

[0053] Figure 4 An example application of an ultrasonic transducer assembly according to an embodiment of the present invention is shown. Depending on actual needs, light (laser beam) from the optical fiber can be transmitted through the microlens by customizing the radius of curvature (of the mold surface and therefore the microlens) and / or the distance between the microlens and the optical fiber. Figure 4 The illustrated adhesive lens is used for collimation or focusing. This invention provides customization capabilities, allowing for the customization or remanufacturing of micro-adhesive lenses integrated with the ultrasound transducer to meet specific specifications or other requirements without altering other components (simply by changing the mold or selecting other photocurable adhesives). Furthermore, the probe or catheter of this application can be used with other components of conventional intravascular ultrasound-photoacoustic endoscopy systems to form novel intravascular ultrasound-photoacoustic endoscopy systems. For example, this system may include a light source (laser light source), controller, signal acquisition unit, signal analysis unit, etc., to perform voltage / current application, signal acquisition, and signal analysis based on ultrasound-photoacoustic dual-mode imaging.

[0054] Furthermore, as mentioned above, this application specifically solves the problems of light supply and device size (rigid length, diameter) by using a photocurable adhesive and a mold to manufacture a micro-adhesive lens located in the ultrasonic transducer and by employing a coaxial arrangement of the device, thus simplifying the manufacturing process of the IVPA probe / catheter. According to this application, a UV-curable adhesive micro-adhesive lens is formed using a photocurable adhesive, especially a UV-curable adhesive, and used in the coaxial design of the IVPA probe / catheter for focusing or collimating light. This allows for focusing or collimating light within a very small space, and the diameter of the microcatheter / probe can be less than 1 mm, and the length can be less than 3 mm. In addition, the catheter / probe with the micro-adhesive lens has a simple structure and a short rigid length, allowing for safer passage through blood vessels for intravascular ultrasound-photoacoustic / dual-mode imaging or endoscopy. Furthermore, the coaxial design allows for a large detection area (ultrasound-photoacoustic overlap area). Furthermore, the method for manufacturing ultrasonic transducer components proposed in this application is simple in process and has strong customization capabilities. It can integrate micro-adhesive lenses with different curvatures, refractive indices and other properties into ultrasonic transducer components according to different needs while keeping other components unchanged.

[0055] Those skilled in the art will understand that various changes and / or modifications can be made to the invention shown in the embodiments without departing from the spirit or scope of the invention as broadly described. Therefore, these embodiments are to be considered illustrative rather than restrictive in all respects.

Claims

1. An ultrasound-optoacoustic probe comprising: an ultrasound transducer assembly for ultrasound / optoacoustic dual-mode imaging of an endoscope, the ultrasound transducer assembly comprising an ultrasound transducer and a micro-lens integrated in the ultrasound transducer, the micro-lens for collimating or focusing a light beam, wherein the micro-lens is integrated in the ultrasound transducer in a manner to be housed in a bore of the ultrasound transducer, wherein the ultrasound transducer is a ring-shaped ultrasound transducer comprising a matching layer, a piezoelectric layer and a backing layer; and the ultrasound-optoacoustic probe further comprising a housing, a mirror, an optical fiber, a coil and an electrical wire, wherein the mirror, the ultrasound transducer assembly and the optical fiber are coaxially arranged in sequence within the housing, the coil is for transmitting a torque and is adapted to be inserted into the housing to cause a scanning motion of the ultrasound transducer assembly, the electrical wire is connected to the ultrasound transducer to induce ultrasound, the optical fiber is optically coupled to the micro-lens, wherein the electrical wire has two electrodes connected to the matching layer and the backing layer of the ring-shaped ultrasound transducer, respectively, and a connection between one of the two electrodes and the matching layer, the connection being configured to be in close proximity to a surface of the mirror facing the matching layer, wherein the micro-lens is a photocured micro-lens cured in the bore of the ultrasound transducer by using a photocured glue, wherein a curvature of the micro-lens is defined by a predetermined curvature of a concave smooth surface provided by a mold.

2. The ultrasound-optoacoustic probe according to claim 1, wherein, the photocured glue is a fast-drying glue with high light transmittance.

3. The ultrasound-optoacoustic probe of claim 2, wherein, the photocured glue is a UV-cured glue and the photocured micro-lens is a UV-cured micro-lens.

4. The ultrasound-optoacoustic probe according to any one of claims 1-3, wherein, a refractive index of the photocured micro-lens is between 1.3-1.

6.

5. The ultrasound-optoacoustic probe according to any one of claims 1-3, wherein, a diameter of the bore is less than 200 pm.

6. The ultrasound-optoacoustic probe according to any one of claims 1-3, wherein, the electrical wire is connected to the ultrasound transducer by a silver glue.

7. The ultrasound-optoacoustic probe according to any one of claims 1-3, wherein, a length of the housing is less than 3 mm and a diameter of the housing is less than 1 mm.

8. An endoscopy system comprising the ultrasound-optoacoustic probe according to any one of claims 1-7.

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