阅读说明：本技术 基于透明柔性复合电极的高灵敏全透明光声探测器及内窥装置 (High-sensitivity full-transparent photoacoustic detector based on transparent flexible composite electrode and endoscopic device ) 是由 杨思华 张道程 张吴昱 张粢鑫 于 2021-07-29 设计创作，主要内容包括：本发明公开了一种基于透明柔性复合电极的高灵敏全透明光声探测器及内窥装置,探测器包括：外壳、保护层、耦合层、匹配层、透明柔性复合电极、透光压电元件、金属环、光学玻璃,光学背衬层和高绝缘电缆；内窥装置包括基于透明柔性复合电极的高灵敏全透明光声探测器、反光镜、光线转换模块、内窥装置外壳、透镜固定模块、微型扫描镜、微电机固定模块、聚焦透镜、透镜垫片、螺旋转接支柱和光纤准直器；本发明优势在于采用高透光性、高导电的柔性透明电极和高耦合系数压电元件制作的超声探测器具有高灵敏度和透光效果,可微型化光声成像探头结构、显著减小工作距离使声场分布均匀和降低系统光路/声路复杂性,推进光声成像向临床转化。(The invention discloses a high-sensitivity full-transparent photoacoustic detector and an endoscopic device based on a transparent flexible composite electrode, wherein the detector comprises: the device comprises a shell, a protective layer, a coupling layer, a matching layer, a transparent flexible composite electrode, a light-transmitting piezoelectric element, a metal ring, optical glass, an optical back lining layer and a high-insulation cable; the endoscopic device comprises a high-sensitivity full-transparent photoacoustic detector based on a transparent flexible composite electrode, a reflector, a light ray conversion module, an endoscopic device shell, a lens fixing module, a micro scanning mirror, a micro motor fixing module, a focusing lens, a lens gasket, a spiral switching strut and an optical fiber collimator; the invention has the advantages that the ultrasonic detector manufactured by the flexible transparent electrode with high light transmission and high conductivity and the piezoelectric element with high coupling coefficient has high sensitivity and light transmission effect, can miniaturize the structure of the photoacoustic imaging probe, obviously reduce the working distance to ensure that the sound field is uniformly distributed, reduce the complexity of the light path/sound path of the system and promote the conversion of photoacoustic imaging to clinic.)

1. A high-sensitivity full-transparent photoacoustic detector based on a transparent flexible composite electrode is characterized by comprising a shell, and a protective layer, a coupling layer, a matching layer, a transparent flexible composite electrode, a light-transmitting piezoelectric element, a metal ring, optical glass, an optical backing layer and a high-insulation cable which are coaxially arranged in the shell; the optical backing layer comprises an outer optical backing layer and an inner optical backing layer; the transparent flexible composite electrode comprises a transparent flexible composite electrode anode and a transparent flexible composite electrode cathode;

the shell is provided with a chamfer and a side wall hole and is used for fixing the detector and grounding the cathode of the transparent flexible composite electrode;

the protective layer is arranged on the top of the shell, is flush with the top of the chamfer and can be directly contacted with a sample to be measured;

the coupling layer is arranged between the upper end of the chamfer and the lower end of the chamfer and is used for transmitting high-frequency ultrasonic waves;

the light-transmitting piezoelectric element is provided with an outer optical back lining layer for position fixing, and is arranged on the inner side of the shell and is parallel to the bottom end of the chamfer of the shell;

the transparent flexible composite electrodes are respectively arranged on the upper end surface and the lower end surface of the light-transmitting piezoelectric element, and the upper ends of the transparent flexible composite electrodes are transparent flexible composite electrode cathodes, namely signal electrode cathodes; the lower end of the piezoelectric element is a transparent flexible composite electrode anode, namely a signal electrode anode, and the area of the transparent flexible composite electrode does not exceed the area of the piezoelectric element;

the metal ring is arranged at the lower end of the transparent flexible composite electrode and is bonded through conductive silver adhesive;

the inner optical backing layer is arranged inside the metal ring, and the height of the inner optical backing layer is the same as that of the metal ring;

the optical glass is disposed under and through the inner optical backing layer;

the high-insulation cable is arranged in a side wall hole of the shell, the cable in the high-insulation cable is connected with the positive electrode of the signal electrode, and the electric shielding layer of the high-insulation cable is connected with the negative electrode of the signal electrode.

2. The high-sensitivity all-transparent photoacoustic detector based on the transparent flexible composite electrode of claim 1, wherein the transparent flexible composite electrode is a conductive film prepared from a silver nanowire solution and a graphene solution together, and the preparation process comprises:

the concentration of 0.4-2 mL is 0.25 mg/mL^-1Coating a silver nanowire solution on the transparent piezoelectric element, wherein the diameter range of the silver nanowire solution is from tens of nanometers to hundreds of nanometers, and rapidly heating, drying and completely evaporating to obtain a nano silver wire electrode conductive film with uniform distribution; coating the conductive film with the nano silver wire electrode with the concentration of 0.2-2 mL and 0.1 mg/mL^-1And (3) irradiating the modified graphene alcohol solution or the reduced and oxidized graphene solution by ultraviolet rays, and quickly heating, drying and completely evaporating to obtain the uniform transparent flexible composite electrode.

3. The transparent and flexible composite electrode-based high-sensitivity and fully transparent photoacoustic detector of claim 1, wherein the transparent piezoelectric element is made of a lithium niobate piezoelectric crystal material or a ferroelectric crystal with high electromechanical coupling coefficient and double-sided polishing polarization, the thickness of the transparent piezoelectric element is 1-500 μm, and the diameter of the transparent piezoelectric element is 1-10 mm.

4. The transparent flexible composite electrode-based high-sensitivity all-transparent photoacoustic detector according to claim 1, wherein the protective layer is a polydimethylsiloxane film with a thickness of 20-500 μm, the polydimethylsiloxane film comprises a siloxane elastomer and a siloxane elastomer curing agent in a mass ratio of 10:1, the polydimethylsiloxane film is uniformly stirred and mixed in a glass vessel, vacuumized, degassed, centrifuged, vacuum degassed again, poured into an acrylic plate, dried and cured, the total-band light transmittance of the obtained PDMS film is greater than 92%, the coupling layer below the PDMS film is a sealed deionized water solution, the acoustic impedance is close to that of biological tissues, and high-frequency acoustic wave conduction is performed.

5. The transparent and flexible composite electrode-based high-sensitivity and fully transparent photoacoustic detector of claim 1, wherein the metal ring is made of brass or stainless steel, the diameter of the metal ring is smaller than that of the piezoelectric element, the range of the diameter is 4-10 mm, and the electrode on one side is led out and the boundary conditions are changed by curing the conductive silver adhesive for more than 24 hours at normal temperature; the height of the epoxy resin material on the inner side is consistent with that of the metal ring, and the optical glass is placed at the top end of the metal ring to prevent the backing from being cured to generate distortion. The conductive silver adhesive is a bi-component adhesive with short curing period and high conductivity, the welding point of the probe shell is formed by stirring and mixing the conductive silver adhesive with the component A and the component B in a mass ratio of 1:1, and the conductive silver adhesive is connected with the radio frequency wire shielding net and the probe shell and is dried and cured.

6. The transparent and flexible composite electrode-based high-sensitivity and fully transparent photoacoustic detector as claimed in claim 1, wherein the optical glass is made of soda-lime glass, the diameter of the optical glass is larger than that of the metal ring and ranges from 8mm to 12mm, and the thickness of the optical glass is 130 μm to 160 μm.

7. The high-sensitivity full-transparent photoacoustic detector based on the transparent flexible composite electrode according to claim 1, wherein the backing material is an optical epoxy resin material, the two-component glue comprises a component A epoxy resin substrate and a component B epoxy resin curing agent, the mass ratio of the two-component glue is 3:1, the two-component glue is uniformly stirred and mixed in a glassware, the two-component glue is vacuumized and degassed, the two-component glue is introduced into a metal ring, polished glass is placed, and the two-component glue is dried and cured to form the optical backing, and the visible light transmittance of the optical backing is greater than 99% @ 400-1200 nm; the matching layer is made of the same optical epoxy resin material, is a two-component glue comprising a component A epoxy resin base material and a component B epoxy resin curing agent, and is obtained by uniformly stirring and mixing the components in a glassware, vacuumizing and degassing, coating the mixture above the transparent flexible composite electrode and curing the mixture, wherein the mass ratio of the two components is 3: 1.

8. The transparent and flexible composite electrode-based high-sensitivity and fully transparent photoacoustic detector according to claim 5, wherein the metal shell is made of stainless steel metal material, the diameter of the metal shell is 6-18 mm, the top end of the metal shell is designed to be an inner chamfer, and holes are punched on the side edges of the metal shell for signal transmission and wiring.

9. The transparent and flexible composite electrode-based highly sensitive and fully transparent photoacoustic detector of claim 5, wherein the highly insulated cable comprises an outer insulating layer, an electrical shielding layer, conductive graphite and an inner cable, and the highly insulated cable has a resistance of >1013 Ω.

10. An endoscopic apparatus comprising the transparent flexible composite electrode-based high-sensitivity fully transparent photoacoustic detector of any one of claims 1 to 9, a reflective mirror, a light conversion module, an endoscopic apparatus housing, a lens fixing module, a micro scanning mirror, a micro motor fixing module, a focusing lens, a lens gasket, a screw adapter strut, and a fiber collimator;

the upper end of the endoscopic device shell is connected with the lower thread of the micromotor fixing module through the upper thread of the endoscopic device shell, and the lower end of the endoscopic device shell is connected with the upper thread of the light conversion module through the lower thread of the endoscopic device shell;

a reflector is embedded in the inner wall of the light ray conversion module, and a high-sensitivity full-transparent photoacoustic detector based on a transparent flexible composite electrode is in threaded connection with the lower part of the light ray conversion module at the lower end;

the inner wall of the micromotor fixing module is embedded into the miniature scanning mirror, and the upper thread of the micromotor fixing module on the right side is connected with the lower thread of the lens fixing module;

the inner side of the lens fixing module is fixed with a focusing lens, and the upper thread of the lens fixing module at the other side is connected with the lower thread of the spiral switching support;

the top end of the spiral switching strut is clamped with the lens gasket, and the screw thread on the spiral switching strut at the other side is connected with the optical fiber collimator;

after the modules are connected, the modules are coaxially arranged with the laser.

Technical Field

The invention relates to the research field of ultrasonic detectors and photoacoustic microimaging, in particular to a high-sensitivity full-transparent photoacoustic detector based on a transparent flexible composite electrode and an endoscopic device.

Background

Photoacoustic imaging is a novel high-specificity and high-contrast mesoscopic imaging technology which has been rapidly developed in the last decade, and is gradually becoming a new research direction of biomedical imaging technology. The imaging technology is based on the photoacoustic effect, a short pulse light source is used as an excitation source to irradiate biological tissues, and photoinduced ultrasonic signals are generated after the biological tissues absorb light energy, so the technology not only has the high selection characteristic of pure optical imaging, but also has the deep penetration characteristic of pure ultrasound, can overcome the limitation of optical scattering in principle, realizes the high contrast and high resolution imaging characteristic of deep living tissues, and can observe the structural and functional characteristics of the biological tissues from the cell scale to the organ span. The technology not only can reflect endogenous substances, such as oxygenated hemoglobin, deoxygenated hemoglobin, melanin, lipid and the like, but also can identify exogenous chromophores with molecular specificity, such as functional optical nanoprobes and the like, with high sensitivity, so that the technology can be widely applied to various fields of biomedicine, including various aspects of tumor biology, vascular biology and the like, and provides powerful technical means for modern precise medical treatment. The photoacoustic endoscope application is an important branch of photoacoustic imaging, which integrates a photoacoustic imaging system into a miniature probe and is applied to combined functional imaging of various cavities such as alimentary tract inflammation detection, intravascular plaque lipid three-dimensional imaging, early gastrointestinal tract tumor identification, Crohn's disease blood vessel characteristic imaging and the like. The photoacoustic endoscope can provide capillary network imaging at a certain depth for tissues and organs and provides a new technical means for diagnosis and treatment of diseases, is suitable for detecting narrow cavities and channels, and needs to realize quick scanning and miniaturization at the same time.

On one hand, the traditional optical-resolution photoacoustic microscopic imaging system has limited field of view of a sound field due to the use of a focusing transducer, not only needs confocal calibration between laser illumination and acoustic detection, but also needs mechanical scanning on an imaging target through an electrode, and greatly limits the photoacoustic imaging speed. On the other hand, the conventional ultrasonic probe has a limitation on miniaturization and workflow of the photoacoustic system because the optical opacity thereof affects the transmission of light. The patent application No. 201610307366.2 discloses a dual frequency hollow focus ultrasound probe whose acoustic field of view is still limited and results in reduced scanned image quality, contrast and sensitivity as the transducer moves away from the central portion. In another side-receiving design, in the setup of an optical resolution photoacoustic microscope, a right-angle prism and an acoustic/optical prism combination of a diamond prism tightly pressed on a layer of thin silicone oil are used to realize coaxial alignment, and photoacoustic waves generated by tissues are transmitted through the diamond prism and reflected by the silicone oil layer to an ultrasonic detector attached to the prism; patent application No. 201911376532.4 discloses a photoacoustic microscopy imaging pen and method of imaging that uses a photoacoustic beam combiner of acoustic reflectors. Such designs require acoustically and optically complex designs, increasing the system working distance, not only would naturally focus the sound field unevenly as the working distance increases, but also required thicker coupling medium (water) between the device and the tissue, introduced artifacts and loss of ultrasound attenuation, resulting in bulky devices, limiting device architecture, and limiting efficiency in terms of depth and resolution. There are also other all-optical ultrasound detection techniques: photonic integrated circuits such as fabry-perot sensors, microring resonators, etc., while these are transparent detection technologies that provide high optical acoustic sensitivity, they require complex fiber integration with additional laser sources and other optical detection instruments.

Disclosure of Invention

The invention mainly aims to overcome the defects of the prior art and provide a high-sensitivity full-transparent photoacoustic detector and an endoscopic device based on a transparent flexible composite electrode, which can reduce the working distance of the system to the maximum extent, increase the field of view, and set the photoacoustic endoscopic imaging system into simple and miniaturized equipment in the endoscope application with limited space, and the optical path and the acoustic path can share the same propagation path.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a high-sensitivity full-transparent photoacoustic detector based on a transparent flexible composite electrode, which comprises a shell, and a protective layer, a coupling layer, a matching layer, a transparent flexible composite electrode, a light-transmitting piezoelectric element, a metal ring, optical glass, an optical backing layer and a high-insulation cable which are coaxially arranged in the shell; the optical backing layer comprises an outer optical backing layer and an inner optical backing layer; the transparent flexible composite electrode comprises a transparent flexible composite electrode anode and a transparent flexible composite electrode cathode;

the shell is provided with a chamfer and a side wall hole and is used for fixing the detector and grounding the cathode of the transparent flexible composite electrode;

the protective layer is arranged on the top of the shell, is flush with the top of the chamfer and can be directly contacted with a sample to be measured;

the coupling layer is arranged between the upper end of the chamfer and the lower end of the chamfer and is used for transmitting high-frequency ultrasonic waves;

the light-transmitting piezoelectric element is provided with an outer optical back lining layer for position fixing, and is arranged on the inner side of the shell and is parallel to the bottom end of the chamfer of the shell;

the transparent flexible composite electrodes are respectively arranged on the upper end surface and the lower end surface of the light-transmitting piezoelectric element, and the upper ends of the transparent flexible composite electrodes are transparent flexible composite electrode cathodes, namely signal electrode cathodes; the lower end of the piezoelectric element is a transparent flexible composite electrode anode, namely a signal electrode anode, and the area of the transparent flexible composite electrode does not exceed the area of the piezoelectric element;

the metal ring is arranged at the lower end of the transparent flexible composite electrode and is bonded through conductive silver adhesive;

the inner optical backing layer is arranged inside the metal ring, and the height of the inner optical backing layer is the same as that of the metal ring;

the optical glass is disposed under and through the inner optical backing layer;

the high-insulation cable is arranged in a side wall hole of the shell, the cable in the high-insulation cable is connected with the positive electrode of the signal electrode, and the electric shielding layer of the high-insulation cable is connected with the negative electrode of the signal electrode.

As a preferred technical scheme, the transparent flexible composite electrode is a conductive film prepared by a silver nanowire solution and a graphene solution together, and the preparation process comprises the following steps:

the concentration of 0.4-2 mL is 0.25 mg/mL^-1Coating a silver nanowire solution on the transparent piezoelectric element, wherein the diameter range of the silver nanowire solution is from tens of nanometers to hundreds of nanometers, and rapidly heating, drying and completely evaporating to obtain a nano silver wire electrode conductive film with uniform distribution; coating the conductive film with the nano silver wire electrode with the concentration of 0.2-2 mL and 0.1 mg/mL^-1And (3) irradiating the modified graphene alcohol solution or the reduced and oxidized graphene solution by ultraviolet rays, and quickly heating, drying and completely evaporating to obtain the uniform transparent flexible composite electrode.

According to a preferable technical scheme, the light-transmitting piezoelectric element is made of a lithium niobate piezoelectric crystal material or a ferroelectric crystal with high electromechanical coupling coefficient and double-sided polishing polarization, the thickness of the light-transmitting piezoelectric element is 1-500 mu m, and the diameter of the piezoelectric element is 1-10 mm.

As a preferred technical scheme, the protective layer is a polydimethylsiloxane film, the thickness of the protective layer is 20-500 mu m, the polydimethylsiloxane film comprises a siloxane elastomer and a siloxane elastomer curing agent, the mass ratio of the polydimethylsiloxane film to the siloxane elastomer curing agent is 10:1, the polydimethylsiloxane film is uniformly stirred and mixed in a glass vessel, vacuumized and degassed, centrifuged, vacuumized and degassed again, poured into an acrylic plate, dried and cured, the full-wave-band light transmittance of the obtained PDMS film is more than 92%, the coupling layer below the PDMS film is a sealed deionized water solution, the acoustic impedance is close to that of biological tissues, and high-frequency sound wave conduction is carried out.

According to a preferable technical scheme, the metal ring is made of brass or stainless steel, the diameter of the metal ring is smaller than that of the piezoelectric element, the range is 4-10 mm, one side electrode is led out through curing of conductive silver adhesive for more than 24 hours at normal temperature, and boundary conditions are changed; the height of the epoxy resin material on the inner side is consistent with that of the metal ring, and the optical glass is placed at the top end of the metal ring to prevent the backing from being cured to generate distortion. The conductive silver adhesive is a bi-component adhesive with short curing period and high conductivity, the welding point of the probe shell is formed by stirring and mixing the conductive silver adhesive with the component A and the component B in a mass ratio of 1:1, and the conductive silver adhesive is connected with the radio frequency wire shielding net and the probe shell and is dried and cured.

According to a preferable technical scheme, the optical glass is made of soda-lime glass, the diameter of the optical glass is larger than that of the metal ring and ranges from 8mm to 12mm, and the thickness of the optical glass ranges from 130 μm to 160 μm.

According to a preferable technical scheme, the backing material is an optical epoxy resin material, belongs to two-component glue and comprises a component A epoxy resin base material and a component B epoxy resin curing agent, the mass ratio of the components is 3:1, the components are uniformly stirred and mixed in a glassware, vacuumized and degassed, introduced into a metal ring, placed with polished surface glass, dried and cured to form an optical backing, and the visible light transmittance of the optical backing is greater than 99% @ 400-1200 nm; the matching layer is made of the same optical epoxy resin material, is a two-component glue comprising a component A epoxy resin base material and a component B epoxy resin curing agent, and is obtained by uniformly stirring and mixing the components in a glassware, vacuumizing and degassing, coating the mixture above the transparent flexible composite electrode and curing the mixture, wherein the mass ratio of the two components is 3: 1.

As the preferred technical scheme, the metal shell is made of stainless steel metal materials, the diameter of the metal shell ranges from 6 mm to 18mm, the top end of the metal shell is designed to be an inner side chamfer, and the side edge of the metal shell is punched and designed to be used for signal transmission to conduct wiring.

Preferably, the high-insulation cable comprises an outer insulation layer, an electric shielding layer, conductive graphite and an inner cable, and the resistance of the high-insulation cable is more than 1013 Ω.

The invention also provides an endoscopic device, which comprises the high-sensitivity full-transparent photoacoustic detector based on the transparent flexible composite electrode, a reflector, a light ray conversion module, an endoscopic device shell, a lens fixing module, a micro scanning mirror, a micro motor fixing module, a focusing lens, a lens gasket, a spiral switching strut and an optical fiber collimator;

the upper end of the endoscopic device shell is connected with the lower thread of the micromotor fixing module through the upper thread of the endoscopic device shell, and the lower end of the endoscopic device shell is connected with the upper thread of the light conversion module through the lower thread of the endoscopic device shell;

a reflector is embedded in the inner wall of the light ray conversion module, and a high-sensitivity full-transparent photoacoustic detector based on a transparent flexible composite electrode is in threaded connection with the lower part of the light ray conversion module at the lower end;

the inner wall of the micromotor fixing module is embedded into the miniature scanning mirror, and the upper thread of the micromotor fixing module on the right side is connected with the lower thread of the lens fixing module;

the inner side of the lens fixing module is fixed with a focusing lens, and the upper thread of the lens fixing module at the other side is connected with the lower thread of the spiral switching support;

the top end of the spiral switching strut is clamped with the lens gasket, and the screw thread on the spiral switching strut at the other side is connected with the optical fiber collimator;

after the modules are connected, the modules are coaxially arranged with the laser.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) the invention adopts the high-sensitivity full-transparent photoacoustic detector based on the transparent flexible composite electrode, the design is easy to realize, the manufacturing cost is controllable, and the finished product effect is obvious; the optical opacity of the conventional ultrasonic detector at present is solved, so that the ultrasonic detector can be miniaturized when applied to a photoacoustic imaging system of the transducer, and the application scenes of the ultrasonic detector are increased.

(2) The invention summarizes experience through experiments, the acoustic characteristic is optimal when the piezoelectric element cut in the Y-36-degree direction is adopted, and visible light transmission of the effect is achieved through double-sided polishing;

(3) the transparent flexible composite electrode prepared by adopting the silver nanowires and the graphene material has excellent light transmission and conductivity, does not have the problem of Morie interference, and is easier to manufacture a detector with high sensitivity and light transmission characteristics.

(4) The invention designs the endoscope by combining the high-sensitivity full-transparent photoacoustic detector based on the transparent flexible composite electrode, has the advantages of miniaturized structure, light volume and hand holding, and can detect the parts with deeper body surface, such as liver, intestine, stomach, ovary, lung, heart, oral cavity, cervix and the like.

Drawings

FIG. 1 is a cross-sectional view of a two-dimensional structure diagram of an ultrasound probe according to an embodiment;

FIG. 2 is a three-dimensional structural view of the present embodiment;

FIG. 3 is a cross-sectional view of the two-dimensional structure of the laparoscope of the present embodiment;

FIG. 4 is a sectional view of a two-dimensional structure of the high-insulation cable according to the embodiment;

FIG. 5 is a distribution diagram of the sound field of the XY plane of the photoacoustic detector of this embodiment;

FIG. 6 is a sound field distribution diagram of different depth distances of the XZ surface of the photoacoustic detector of this embodiment;

FIG. 7 is a time domain signal diagram of the present embodiment;

FIG. 8 is a frequency domain signal diagram of the present embodiment;

fig. 9 is a manufacturing flowchart of the present embodiment.

The reference numbers illustrate:

a-incident laser, U is a high-sensitivity full-transparent photoacoustic detector based on a transparent flexible composite electrode, 10 is a shell, 11 is a shell thread, 12 is a shell side wall hole, 13 is a shell chamfer, 13-1 is a shell chamfer top end, 13-2 is a shell chamfer bottom end, 20 is a protective layer, 21 is a coupling layer, 22 is a matching layer, 30 is a transparent flexible composite electrode, 30-1 is a transparent flexible composite electrode anode, 30-2 is a transparent flexible composite electrode cathode, 31 is a light-transmitting piezoelectric element, 32 is conductive silver adhesive, 33 is a metal ring, 40 is an optical backing layer, 40-1 is an inner optical backing layer, 40-2 is an outer optical backing layer, 41 is optical glass, 50 is a high-insulation cable, 50-1 is an inner cable, 50-2 is an electrical insulation layer, 50-3 is a special sheath, and 50-4 is an electrical shielding layer, 50-5 is an outer insulating layer, 60 is an optical fiber collimator, 61 is a focusing lens, 62 is a lens gasket, 63 is a reflector, 64 is a micro scanning mirror, 70 is an endoscopic device shell, 70-1 is an endoscopic device shell upper thread, 70-2 is an endoscopic device shell lower thread, 71 is a spiral switching support, 71-1 is a spiral switching support upper thread, and 71-2 is a spiral switching support lower thread; 72 is a lens fixing module, 72-1 is upper threads of a mirror fixing module, and 72-2 is lower threads of the mirror fixing module; 73 is a micromotor fixing module, 73-1 is an upper thread of the micromotor fixing module, and 73-2 is a lower thread of the micromotor fixing module; 74 is the light conversion module, 74-1 is the light conversion module upper thread, and 74-2 is the light conversion module lower thread.

Detailed Description

In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The working principle of the scheme is that incident pulse laser A enters an optical channel and then sequentially passes through transducer optical glass 41, an inner side optical back lining layer 40-1, a transparent flexible composite electrode cathode 30-2, a light-transmitting piezoelectric element 31, a transparent flexible composite electrode anode 30-1, a coupling layer 21 and a matching layer 22 to reach a final tested sample, an ultrasonic signal is excited, an ultrasonic echo signal returns to a high-sensitivity full-transparent photoacoustic detector U based on a transparent flexible composite electrode along an original optical path, and the generated electric signal is conducted after passing through a high-insulation cable 50.

As shown in fig. 1 and fig. 2, the high-sensitivity fully transparent photoacoustic detector U based on the transparent flexible composite electrode of the present embodiment includes: the optical fiber laser comprises a shell 10, a protective layer 20, a coupling layer 21, a matching layer 22, a transparent flexible composite electrode 30, a light-transmitting piezoelectric element 31, a metal ring 33, optical glass 41, an optical backing layer 40 and a high-insulation cable 50, wherein the protective layer 20, the coupling layer 21, the matching layer 22, the transparent flexible composite electrode 30, the light-transmitting piezoelectric element 31, the metal ring 33 and the optical glass 41 are coaxially arranged in the shell, and during operation, incident laser A is emitted out from a cavity formed by coaxially arranging components such as the shell.

The shell is provided with a shell chamfer 13, a side wall opening 12 and a shell thread 11, so that a high-sensitivity full-transparent photoacoustic detector U based on the transparent flexible composite electrode can be fixed, and the cathode 31-2 of the transparent flexible composite electrode is grounded.

The protective layer 20 is arranged on the top of the shell 10 and is flush with the top end 13-1 of the chamfer of the shell, and can be directly contacted with a sample to be measured.

The coupling layer 21 is arranged between the top end 13-1 of the outer shell chamfer and the bottom end 13-2 of the outer shell chamfer and is used for transmitting high-frequency ultrasonic waves.

The optically transparent piezoelectric element 31 is provided with an outer backing layer for positional fixation and is fitted inside the housing 10 parallel to the chamfered bottom end 13-2 of the housing.

The transparent flexible composite electrodes 30 are respectively arranged on the upper end face and the lower end face of the light-transmitting piezoelectric element 31, the upper ends of the transparent flexible composite electrodes are transparent flexible composite electrode cathodes 30-2, namely signal electrode cathodes, and the lower ends of the transparent flexible composite electrode anodes 30-1, namely signal electrode anodes, and the area of the transparent flexible composite electrodes 30 is not more than that of the light-transmitting piezoelectric element 31.

The metal ring 33 is disposed at the lower end of the transparent flexible composite electrode 30 and is bonded by the conductive silver paste 32.

The optical backing layer 40 includes an inner optical backing layer 40-1 and an outer optical backing layer 40-2, the inner optical backing layer 40-1 being disposed inside the metal ring 33 and having a height corresponding to the height of the metal ring 33.

The optical glass 41 is disposed beneath and through the inner optical backing layer 40-1 to prevent distortion of the inner optical backing layer 40-1 during curing.

The high-insulation cable 50 is arranged in the side wall hole 12 of the shell, wherein the cable 50-1 is connected with the positive electrode 30-1 of the transparent flexible composite electrode, and the electric shielding layer 50-4 is connected with the negative electrode 30-2 of the transparent flexible composite electrode.

Further, the transparent flexible composite electrode 30 is a conductive film prepared by a silver nanowire solution and a graphene solution together, and the concentration of 0.4-2 mL is 0.25 mg/mL^-1Coating a silver nanowire solution on the transparent piezoelectric element 31, wherein the diameter of the silver nanowire solution ranges from tens of nanometers to hundreds of nanometers, and completely drying and evaporating the silver nanowire solution in an oven at 100 ℃ to obtain a conductive film with a nano silver wire electrode; to pairThe conductive film coating with the nano silver wire electrode has a concentration of 0.1 mg/mL to 0.2-2 mL^-1And irradiating the modified graphene alcohol solution or the reduced and oxidized graphene solution by ultraviolet rays, and drying and completely evaporating the modified graphene alcohol solution or the reduced and oxidized graphene solution in an oven at 100 ℃ to obtain the transparent flexible composite electrode 30. The performance ratio of the silver nanowires to the ITO, metal grid is shown in table 1.

TABLE 1

It is understood that, in order to obtain better photoacoustic imaging effect, theoretically, the basic equation of photoacoustic theory is utilized:

and deducing the relation between the photoacoustic signal and the time t and the distance r, analyzing the distribution condition of the photoacoustic field, and finding that the closer the photoacoustic signal is to the sound source, the higher the photoacoustic pressure is.

Through a calculation formula of sound pressure in acoustics:

the sound pressure distribution of the photoacoustic detector can be deduced, and the field dii toolkit of Matlab software is simulated to obtain the XY-plane sound field distribution diagram and the XZ-plane of the photoacoustic detector of the embodiment at various distances as shown in fig. 5 and 6, so that different dimensions of the photoacoustic detector are designed.

Further, the light-transmitting piezoelectric element 31 uses double-side polished polarized lithium niobate (LiNbO) with high electromechanical coupling coefficient₃) Piezoelectric crystal material or Pb (Mg)_1/3Nb_2/3)O₃-PbTiO₃The (PMN-PT) ferroelectric crystal has a thickness of 1-500 μm, the diameter of the light-transmitting piezoelectric element 31 is 1-10 mm, and the cutting direction of the light-transmitting piezoelectric element 31 can be different directions, preferably the light-transmitting piezoelectric element 31 cut in the Y-36 degree direction, as shown in Table 2.

TABLE 2

Further, the protective layer 20 is a polydimethylsiloxane film (PDMS) with a thickness of 20-500 μm, the PDMS film comprises a siloxane elastomer and a siloxane elastomer curing agent in a mass ratio of 10:1, the PDMS film is uniformly stirred and mixed in a glass vessel, subjected to vacuum degassing, centrifuged, subjected to vacuum degassing again, poured into an acrylic plate, dried and cured, and has a full-wave-band light transmittance of more than 92%, the coupling layer 21 below the PDMS film is a deionized water solution, has a similar acoustic impedance to a biological tissue, and performs high-frequency sound wave conduction, and the coupling layer 21 is used for providing acoustic coupling between an imaging window and the photoacoustic detector U in the probe.

Further, the metal ring 33 is made of brass or stainless steel material, the diameter of the metal ring is smaller than that of the piezoelectric element 31, the range is 4-10 mm, one side electrode is led out through curing of conductive silver adhesive for more than 24 hours at normal temperature, and boundary conditions are changed; the inner optical backing layer 40-1 is kept at the same height as the metal ring 33, and the optical glass 41 is placed on the top end to prevent the optical backing layer from being cured to generate distortion. The conductive silver adhesive 32 is a bi-component adhesive with short curing period and high conductivity, the welding point of the probe shell is formed by stirring and mixing the conductive silver adhesive with the component A and the component B in a mass ratio of 1:1, connecting the electric shielding layer 50-4 with the shell 10, and drying and curing.

Furthermore, the optical glass 41 is made of soda-lime glass, the diameter of the optical glass is larger than that of the metal ring 33, the range of the optical glass is 8-12 mm, and the thickness of the optical glass is 130-160 μm.

Further, the optical backing layer 40 is an optical epoxy resin material, belongs to two-component glue and comprises a component A epoxy resin base material and a component B epoxy resin curing agent, the mass ratio of the components is 3:1, the components are uniformly stirred and mixed in a glassware, vacuumized and degassed, guided into a metal ring, placed with polished surface glass, dried and cured to form the optical backing layer 40, and the visible light transmittance of the optical backing layer is greater than 99% @ 400-1200 nm; the matching layer 22 is made of the same optical epoxy resin material, is a two-component glue comprising a component A epoxy resin base material and a component B epoxy resin curing agent, and is prepared by uniformly stirring and mixing the components in a glassware with the mass ratio of 3:1, vacuumizing and degassing, coating the mixture on a transparent flexible composite electrode cathode 30-2, and curing the mixture to obtain the matching layer 22.

Further, the conductive silver adhesive 32 is a bi-component type adhesive with high conductivity and short curing period, the welding point of the probe shell is formed by mixing the conductive silver adhesive component A and the conductive silver adhesive component B in a mass ratio of 1:1, and the mixture is stirred, mixed, connected with the radio frequency wire shielding net and the probe shell, dried and cured.

Furthermore, metal casing be stainless steel metal material, diameter 6 ~ 18mm, the top is the design of inboard chamfer, the outside design of punching is used for signal transmission to walk the line.

Preferably, the signal transmission line is a highly insulated cable 50 comprising an outer insulating layer 50-5, an electrical shielding layer 50-4, a special sheath 50-3 (conductive graphite), an electrical insulating layer 50-2, and an inner cable 50-1, as shown in fig. 4, the resistance of the highly insulated cable is >1013 Ω.

Finally, through the manufacturing flow chart of this embodiment as shown in fig. 9, the manufacturing steps of the manufactured high-sensitivity fully-transparent photoacoustic detector based on the transparent flexible composite electrode are as follows:

(1) placing the cut light-transmitting piezoelectric element 31 on an acrylic plate, and uniformly coating the transparent flexible composite electrode 30 on two sides of the light-transmitting piezoelectric element 31;

(2) placing an outer optical back lining layer 40-2 on the acrylic plate, placing a conductive silver wire at the upper end of a light-transmitting piezoelectric element 31 with a transparent flexible composite electrode 30, and carrying out compression molding on quartz glass with a release agent;

(3) placing the inverted light-transmitting piezoelectric element 31 on an acrylic plate, placing a metal ring 33 uniformly coated with conductive silver adhesive on the metal ring 33, wherein the inner optical backing layer 40-1 is arranged in the metal ring 33, and preventing the curing distortion of the inner optical backing layer 40-1 by using optical glass 41;

(4) the core part of the formed high-sensitivity full-transparent transducer U based on the transparent flexible composite electrode is arranged in a metal shell 10, and the metal shell is fixed in position by sealing and pouring glue;

(5) the top end of the high-sensitivity full-transparent transducer U based on the transparent flexible composite electrode is provided with a PDMS material protective layer 20, and a piezoelectric signal generated by the light-transmitting piezoelectric element 31 is derived by using a high-insulation cable 50.

Further, after the high-sensitivity fully transparent photoacoustic probe is manufactured, a pulse ultrasonic echo experiment is performed to obtain a time domain signal diagram of the embodiment shown in fig. 7 and a frequency domain signal diagram of the embodiment shown in fig. 8.

As shown in fig. 3, another aspect of the present invention provides an endoscopic apparatus for a transparent flexible composite electrode based high-sensitivity all-transparent photoacoustic probe, which includes a transparent flexible composite electrode based high-sensitivity all-transparent photoacoustic probe U, a reflective mirror 63, a light conversion module 74, an endoscopic apparatus housing 70, a lens fixing module 72, a micro scanning mirror 64, a micro motor fixing module 73, a focusing lens 61, a lens gasket 62, a screw adapter strut 71, and a fiber collimator 60.

The upper end of the endoscopic device shell 70 is connected with the lower thread 73-2 of the micromotor fixing module through the upper thread 70-1 of the endoscopic device shell, and the lower end is connected with the upper thread 74-1 of the light conversion module through the lower thread 70-2 of the endoscopic device shell.

The inner wall of the light ray conversion module 74 is embedded into the reflector 63, and the lower thread 74-2 of the light ray conversion module at the lower end is connected with a high-sensitivity full-transparent photoacoustic detector U based on a transparent flexible composite electrode.

The inner wall of the micromotor fixed module 73 is embedded into the miniature scanning mirror 64, and the upper thread 73-1 of the micromotor fixed module at the right side is connected with the lower thread 72-2 of the lens fixed module.

The lens fixing module 72 fixes the focusing lens 61 on the inner side, and the upper thread 72-1 of the lens fixing module on the other side is connected with the lower thread 71-1 of the screw adapter strut.

The top end of the spiral switching strut 71 is clamped with the lens gasket 63, and the thread 71-1 on the spiral switching strut on the other side is connected with the optical fiber collimator 60;

after the modules are connected, the modules are coaxially arranged with the laser.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.