An ultrasonic coupling material with gradually varying acoustic impedance for enhancing transmission

Abstract

The present invention discloses an antireflection ultrasonic coupling material with gradually changing acoustic impedance. By introducing a wedge structure with parallel bottoms and complementary opposed sides, the gradual change of acoustic impedance is achieved. This structure includes two wedge structures with different acoustic impedances, and the acoustic impedance at different positions in the sound wave propagation direction can be equivalent to the average value of the acoustic impedances of the two wedges. Through the present invention, a continuous change in acoustic impedance is achieved between the piezoelectric material and the object to be measured, that is, ultrasonic waves can propagate more smoothly between the piezoelectric material and the object to be measured, significantly reducing the reflection of ultrasonic waves, allowing more energy to enter the human tissue. At the same time, the echo signal is stronger and the imaging image is clearer, thereby improving the ultrasonic transmission ability, ultrasonic detection accuracy and efficiency, and having broad technical application potential.

Description

Technical Field

[0001] The present invention relates to the field of new medical ultrasound materials, and particularly to an ultrasound coupling material with a gradually changing acoustic impedance for enhancing the transmission ability of ultrasonic waves and improving the effects of ultrasonic detection and treatment. Background Art

[0002] Ultrasonic waves are of great significance in aspects such as clinical disease diagnosis, adjuvant treatment, and detection of treatment effects.

[0003] When ultrasonic waves propagate in different media, due to the difference in acoustic impedance, reflection and refraction occur at the interface, resulting in energy loss of the ultrasonic wave signal and reducing the performance and clinical effects of ultrasonic equipment. To solve the above problems, an acoustic impedance matching material is filled between the ultrasonic transducer and the object to be measured or the treatment object. This material can provide an acoustic impedance matching effect and achieve a gradual transition of acoustic impedance, which is of great significance for improving the effects and application scope of ultrasonic technology and is widely used in fields such as disease diagnosis, non-invasive ultrasonic treatment, and ultrasonic non-destructive testing.

[0004] For a general acoustic impedance matching material, its acoustic impedance is between the acoustic impedance of the piezoelectric material of the ultrasonic transducer and the acoustic impedance of the object to be measured, and it is bonded to the front end of the ultrasonic transducer to promote the propagation of ultrasonic waves from the ultrasonic transducer into the object to be measured. However, when the difference in acoustic impedance between the piezoelectric material of the ultrasonic transducer and the acoustic impedance of the object to be measured is relatively large, a single-layer acoustic impedance matching material often has insufficient effect, and a double-layer or even multi-layer acoustic impedance matching material needs to be used. For example, the Chinese invention patent "Matching layer of ultrasonic transducer stack, ultrasonic transducer stack, and method for producing a matching layer of ultrasonic transducer stack" (publication number CN 103861796A) proposes a structure and processing method of a multi-layer matching material. However, this multi-layer matching material has deficiencies. That is, this matching material is composed of multiple different matching layers bonded by an adhesive, and the acoustic impedance of the adhesive is inconsistent with the acoustic impedance of the matching material, that is, the presence of the adhesive makes the acoustic impedance between the adhesive layer and the matching material layer discontinuous, which in turn limits the exertion of the ultrasonic transmission effect of this multi-layer matching material to a certain extent, especially when the ultrasonic frequency is high and the wavelength is short, the negative impact is greater. In addition, if this multi-layer matching processing method is to achieve the effect of gradually changing acoustic impedance, the matching layer needs to be divided into a very large number of stacked layers, which increases the processing complexity and reduces the yield rate. Summary of the Invention

[0005] One of the objectives of the present invention is to provide an ultrasonic coupling material with gradually varying acoustic impedance to solve the above technical problems, achieving gradually varying acoustic impedance without introducing additional adhesives. This ultrasonic matching material structure with gradually varying acoustic impedance adopts two wedge structures with parallel bottoms and complementary opposite arrangements, including a first wedge structure and a second wedge structure. When sound waves propagate in this ultrasonic coupling material with enhanced transmission, the acoustic impedance at different positions in the sound wave propagation direction can be equivalent to the average value of the acoustic impedances of the two wedge structures. In the sound wave propagation direction, since the proportion of the two wedge structures changes continuously, the acoustic impedance of the ultrasonic coupling material with enhanced transmission also varies gradually. The acoustic impedance of each of the two wedge structures can be adjusted by changing the type and proportion of the internal particulate matter doping to adapt to different piezoelectric materials and the situation of the object to be measured;

[0006] To achieve the above patent objectives, the technical solutions adopted by the present invention are as follows:

[0007] 1. Wedge structure design:

[0008] As shown in the appendix Figure 1 A ultrasonic coupling material with gradually varying acoustic impedance is placed on the piezoelectric material of the ultrasonic transducer. This ultrasonic coupling material with enhanced transmission is in close contact with the object to be measured and can form an acoustic impedance transition between the piezoelectric material and the object to be measured. The ultrasonic coupling material with gradually varying acoustic impedance is divided into a first wedge structure and a second wedge structure. These two wedge structures are arranged in a way that their bottoms are parallel and complementary to each other. They are formed by mixing and solidifying the same homogeneous base material and particulate matter incorporated therein. Among them, each of the first wedge structure and the second wedge structure contains a kind of particulate matter, and the types of particulate matter contained are different;

[0009] An ultrasonic coupling material with gradually varying acoustic impedance includes two wedge structures with different acoustic impedances, namely a first wedge structure and a second wedge structure. These two wedge structures are arranged in a way that their bottoms are parallel and complementary to each other. The first wedge structure and the second wedge structure are formed by mixing and solidifying the same homogeneous base material and particulate matter incorporated therein. Among them, each of the first wedge structure and the second wedge structure contains a kind of particulate matter, and the types of particulate matter contained are different;

[0010] To better implement the present invention, further, the bottom width W of the wedge structure is less than 1 / 4 of the wavelength of the sound wave corresponding to the center frequency of the ultrasonic transducer in the base material;

[0011] To better implement the present invention, further, the radius λ of the particulate matter is less than 1 / 40 of the wavelength of the sound wave corresponding to the center frequency of the ultrasonic transducer in the base material;

[0012] To better implement the present invention, further, the thickness H of the ultrasonic coupling material with gradually changing acoustic impedance is an odd multiple of 1 / 4 of the arithmetic mean of the wavelengths of the sound waves corresponding to the center frequency of the ultrasonic transducer in the piezoelectric material and the object to be measured, respectively;

[0013] To better implement the present invention, further, the acoustic impedances of the first wedge structure and the second wedge structure are Z1 and Z2 respectively, and the equivalent acoustic impedance at different positions in the sound wave propagation direction is calculated by weighting according to the proportion of the two wedge materials and the specific values of Z1 and Z2;

[0014] To better implement the present invention, further, the substrate material is one of epoxy resin or PDMS material;

[0015] 2. Realization of gradually changing acoustic impedance:

[0016] The acoustic impedances of the first wedge structure and the second wedge structure are Z1 and Z2 respectively. By changing the types and proportions of the internal particulate additives of the wedge materials, the equivalent acoustic impedance after the synthesis of the two wedge structures is adjusted to adapt to different piezoelectric materials and objects to be measured;

[0017] To better implement the present invention, further, the acoustic impedance Z1 of the first wedge structure depends on the equivalent acoustic impedance after mixing the substrate material with acoustic impedance Zb and the additive 1 with acoustic impedance Zd1, where the acoustic impedance Zd1 of the additive 1 is greater than the acoustic impedance Zp of the piezoelectric material, and Zb + Zd1 > 2 × Zp;

[0018] To better implement the present invention, further, the acoustic impedance Z2 of the second wedge structure depends on the equivalent acoustic impedance after mixing the substrate material with acoustic impedance Zb and the additive 2 with acoustic impedance Zd2, where the acoustic impedance Zd2 of the additive 2 is less than the acoustic impedance Zt of the target object, and Zb + Zd2 < 2 × Zt;

[0019] To better implement the present invention, further, the particulate matter is the additive 1 with acoustic impedance greater than Zp and the additive 2 with acoustic impedance less than Zt;

[0020] To better implement the present invention, further, the acoustic impedances of the additive 1 and the additive 2 need to meet the technical requirements, and at the same time, they should be easy to process and easy to mix with the substrate material;

[0021] To better implement the present invention, further, the additive 1 is preferably tungsten powder, and the additive 2 is preferably hollow glass microspheres;

[0022] To better implement the present invention, further, the additive 1 is incorporated into the first wedge structure, and the additive 2 is incorporated into the second wedge structure;

[0023] To better implement the present invention, further, the shape of the wedge structure is an isosceles triangle, and the bottom width W is less than 1 / 4 of the wavelength of the sound wave corresponding to the center frequency of the ultrasonic transducer in the substrate material;

[0024] To better implement the present invention, further, the ultrasonic transducer acting device of the ultrasonic coupling material with gradually changing acoustic impedance includes: a piezoelectric material for emitting ultrasonic waves;

[0025] To better implement the present invention, further, the ultrasonic coupling material with gradually changing acoustic impedance is closely attached between the piezoelectric material of the ultrasonic transducer and the object to be measured to achieve a gradual transition of the acoustic impedance;

[0026] To better implement the present invention, further, the ultrasonic transducer acting device significantly improves the transmission ability and focusing accuracy of ultrasonic waves through the ultrasonic coupling material with gradually changing acoustic impedance;

[0027] To better implement the present invention, further, the ultrasonic transducer acting device is characterized in that: the ultrasonic transducer is a circular or array transducer, and the emission frequency, power and pulse parameters are tuned by an external control system;

[0028] To better implement the present invention, further, the transcranial ultrasonic therapy device of the ultrasonic coupling material with gradually changing acoustic impedance includes: an ultrasonic transducer for emitting ultrasonic waves;

[0029] To better implement the present invention, further, the ultrasonic coupling material with gradually changing acoustic impedance is closely attached between the piezoelectric material of the ultrasonic transducer and the skull to enhance the transmission ability of ultrasonic waves;

[0030] To better implement the present invention, further, the transcranial ultrasonic therapy device significantly improves the efficiency and accuracy of transcranial ultrasonic therapy through the ultrasonic coupling material with gradually changing acoustic impedance;

[0031] To better implement the present invention, further, the transcranial ultrasonic therapy device is characterized in that: the operating frequency of the ultrasonic transducer is 0.1 MHz - 3 MHz, which is suitable for transcranial ultrasonic neuromodulation and therapy;

[0032] To better implement the present invention, further, the ultrasonic nondestructive testing device of the ultrasonic coupling material with gradually changing acoustic impedance includes: an ultrasonic transducer for emitting ultrasonic waves;

[0033] To better implement the present invention, further, the ultrasonic coupling material with gradually changing acoustic impedance is closely attached between the piezoelectric material of the ultrasonic transducer and the object to be measured to enhance the transmission ability of ultrasonic waves;

[0034] To better implement the present invention, further, the ultrasonic nondestructive testing device significantly improves the accuracy and efficiency of ultrasonic testing through the ultrasonic coupling material with gradually changing acoustic impedance.

[0035] The second object of the present invention is to provide a preparation method of an ultrasonic coupling material with gradually changing acoustic impedance, and this method is carried out according to the following operating steps:

[0036] (1) Calculate the acoustic impedance of the first wedge structure and the second wedge structure and the corresponding proportion of the particulate matter content according to the acoustic impedance of the piezoelectric material and the acoustic impedance of the object to be measured;

[0037] (2) Mix the base material and particulate matter 1 to make a preparation material for the first wedge structure, and bond the preparation material for the first wedge structure to the emitting surface of the piezoelectric material of the ultrasonic transducer through a die casting or prefabrication into a layered process to obtain a quasi-structure of the first wedge structure;

[0038] (3) Carry out laser layer-by-layer etching on the quasi-structure of the first wedge structure to obtain the first wedge structure;

[0039] (4) Mix the base material and particulate matter 2 to make a preparation material for the second wedge structure, load the preparation material for the second wedge structure into the gap of the first wedge structure through a die casting process, and then solidify to form a complete ultrasonic coupling material with gradually changing acoustic impedance.

[0040] The present invention can be used for transcranial detection, coronary stent drug release, coronary balloon drug release, etc.

[0041] Advantages of the present invention:

[0042] After adopting the ultrasonic coupling material with gradually changing acoustic impedance, a continuous change in acoustic impedance is achieved between the piezoelectric material and the object to be measured, that is, ultrasonic waves can propagate more smoothly between the piezoelectric material and the object to be measured, significantly reducing the reflection of ultrasonic waves, allowing more energy to enter the human tissue. At the same time, the echo signal is stronger and the imaging is clearer, thereby improving the ultrasonic transmission ability and the accuracy and efficiency of ultrasonic testing.

[0043] Taking transcranial focused ultrasound for the treatment of brain diseases as an example, the energy loss of the transcranial sound field without using the ultrasonic coupling material with gradually changing acoustic impedance is relatively large, and the maximum sound pressure at the focus is only about 9 kPa, while the maximum sound pressure at the focus of the transcranial sound field after using the ultrasonic coupling material with gradually changing acoustic impedance increases to about 60 kPa, and its energy is significantly greater than that of the transcranial sound field without using the ultrasonic coupling material with gradually changing acoustic impedance. Description of the Drawings

[0044] Figure 1 Schematic three-dimensional diagram of the ultrasonic coupling material for enhancing penetration

[0045] Figure 2 Schematic diagram of the cross-sectional structure and application of an anti-reflection ultrasonic coupling material

[0046] Figure 3 Transcranial acoustic field detection result diagram without using an anti-reflection ultrasonic coupling material

[0047] Figure 4 Transcranial acoustic field detection result diagram after using an anti-reflection ultrasonic coupling material

[0048] Figure 5 Processing flow chart of the anti-reflection ultrasonic coupling material

[0049] Figure 6 Schematic diagram of laser layer-by-layer etching Specific implementation manners

[0050] The technical solutions of the present invention will be further described in detail below in combination with specific embodiments and comparative examples. However, the present invention is not limited by these specific embodiments, and it is an explanation rather than a limitation of the present invention.

[0051] The following are the embodiments and comparative examples.

[0052] Example 1

[0053] Mix epoxy resin as the base material accounting for 34% and tungsten powder as particulate additive 1 accounting for 66% to obtain a first wedge structure preform; through the die casting process, bond the first wedge structure preform to the emitting surface of the piezoelectric material PZT-4 of the ultrasonic transducer to obtain a first wedge structure quasi-structure;

[0054] Subsequently, perform laser layer-by-layer etching on the first wedge structure quasi-structure to obtain a first wedge structure;

[0055] Mix epoxy resin as the base material accounting for 83% and hollow glass microspheres as particulate additive 2 accounting for 17% to obtain a second wedge structure preform; through the die casting process, load the second wedge structure preform into the voids of the first wedge structure, and then cure to form a complete anti-reflection ultrasonic coupling material with a gradually changing acoustic impedance.

[0056] Comparative Example 1

[0057] Comparative Example 1 is basically the same as Example 1, except that: the ultrasonic coupling material does not adopt a wedge structure, but adopts a traditional multi-layer matching layer structure, and the layers are adhered with glue.

[0058] The transcranial acoustic field sound pressure was detected for the above Example 1 and Comparative Example 1, and the results are shown in Table 1; the acoustic impedances of the first inclined wedge structure, the second inclined wedge structure, the piezoelectric material PZT-4, and the human tissue in Example 1 were detected respectively, and the results are shown in Table 2; the transcranial acoustic field sound pressure was detected for the two cases of using Example 1 of the present invention and not using the present invention, and the results are as shown in the attached Figure 3 and the attached Figure 4 .

[0059] Table 1 Results of transcranial acoustic field sound pressure detection for Example 1 and Comparative Example 1

[0060]

[0061] Table 2 Acoustic impedance detection results

[0062]

[0063] Judging from the results in Table 1 and Table 2, a sound-transmitting ultrasonic coupling material with a gradually changing acoustic impedance can make the sound wave propagate more smoothly from the piezoelectric material to the object to be measured, achieve an effective transition of the acoustic impedance, and significantly improve the transmission ability of the ultrasonic wave. Among them, in Comparative Example 1, the inclined wedge structure was not used, but the traditional multi-layer matching layer structure was used. As a result, the sound pressure was relatively low and more sound waves were wasted, indicating that the traditional multi-layer matching structure is not conducive to sound wave transmission. The reason is that this traditional structure is made of flat matching layers glued together layer by layer, and the glue layer has a certain thickness. When the frequency of the transducer is very high (corresponding to a very short wavelength), the glue layer will cause a jump in the acoustic impedance, making the acoustic impedance between the bonding layer and the matching material layer discontinuous, which is not conducive to sound wave transmission, especially when the ultrasonic frequency is high and the wavelength is short, the negative impact is greater.

[0064] Judging from the attached Figure 3 and the attached Figure 4 , taking the transcranial focused ultrasound for the treatment of brain diseases as an example, the energy loss of the transcranial sound field without using the sound-transmitting ultrasonic coupling material with a gradually changing acoustic impedance is relatively large, and the maximum sound pressure at the focal point is only about 9 kPa. However, after using the sound-transmitting ultrasonic coupling material with a gradually changing acoustic impedance, the maximum sound pressure at the focal point of the transcranial sound field increases to about 60 kPa, and its energy is significantly greater than that of the transcranial sound field without using the sound-transmitting ultrasonic coupling material with a gradually changing acoustic impedance.

[0065] In summary, the above results show that the sound-transmitting ultrasonic coupling material with a gradually changing acoustic impedance designed by the present invention can, to a certain extent, achieve an effective transition of the acoustic impedance, promote the propagation of sound waves, and thus improve the transmission ability, accuracy and efficiency of ultrasonic waves.

[0066] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be realized that the above description should not be considered as a limitation to the present invention. After those skilled in the art have read the above content, various modifications and alternatives to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. An anti-transmission ultrasonic coupling material with a gradual change in acoustic impedance, characterized in that: The invention comprises two oblique split structures with different acoustic impedances, namely a first oblique split structure and a second oblique split structure, wherein the two oblique split structures are arranged in a manner that the bottom sides are parallel and opposed to each other and complement each other; the first oblique split structure and the second oblique split structure are formed by mixing and solidifying the same homogeneous base material and particles mixed therein, wherein the first oblique split structure and the second oblique split structure each contain at least one particle, and the types of the particles contained are different; The bottom width W of the oblique split structure is less than 1 / 4 of the wavelength of the sound wave corresponding to the center frequency of the ultrasonic transducer in the base material; the radius λ of the particle is less than 1 / 40 of the wavelength of the sound wave corresponding to the center frequency of the ultrasonic transducer in the base material; the thickness H of the acoustic impedance gradient anti-reflection ultrasonic coupling material is an odd multiple of 1 / 4 of the arithmetic mean of the wavelength of the sound wave corresponding to the center frequency of the ultrasonic transducer in the piezoelectric material and the object under test respectively; the acoustic impedances of the first oblique split structure and the second oblique split structure are Z1 and Z2 respectively, and the equivalent acoustic impedances at different positions in the direction of sound wave propagation are weightedly calculated according to the proportions of the two oblique split materials and the specific values ​​of Z1 and Z2; The preparation method comprises the following steps: (1) Calculate the acoustic impedance of the first wedge structure and the second wedge structure and the corresponding particle content ratio based on the acoustic impedance of the piezoelectric material and the acoustic impedance of the object to be tested; (2) mixing the base material and the granular material 1 to form a first oblique split structure preparation material, and bonding the first oblique split structure preparation material to the emitting surface of the piezoelectric material of the ultrasonic transducer through mold casting or prefabrication into a layered process to obtain a first oblique split structure quasi-structure; (3) performing laser etching layer by layer on the first oblique-wedge structure quasi-structure to obtain a first oblique-wedge structure; (4) The base material and the particle 2 are mixed to form a second oblique wedge structure preparation material, and the second oblique wedge structure preparation material is loaded into the gap of the first oblique wedge structure through a mold casting process, and then solidified to form a complete acoustic impedance gradient anti-reflection ultrasonic coupling material.

2. The anti-transmission ultrasonic coupling material with a gradient acoustic impedance according to claim 1, characterized in that: The acoustic impedance Z1 of the first wedge structure depends on the equivalent acoustic impedance of a mixture of a base material with an acoustic impedance Zb and an admixture 1 with an acoustic impedance Zd1, wherein the acoustic impedance Zd1 of the admixture 1 is greater than the acoustic impedance Zp of the piezoelectric material, and Zb+Zd1>Zp×2.

3. The anti-transmission ultrasonic coupling material with a gradient acoustic impedance according to claim 1, characterized in that: The acoustic impedance Z2 of the second wedge structure depends on the equivalent acoustic impedance of the base material with an acoustic impedance of Zb and the admixture 2 with an acoustic impedance of Zd2, wherein the acoustic impedance Zd2 of the admixture 2 is less than the acoustic impedance Zt of the target object, and Zb+Zd2 <Zt×2。 4. The anti-transmission ultrasonic coupling material with a gradient acoustic impedance according to claim 1, characterized in that: The base material is one of epoxy resin and PDMS material.

5. The anti-transmission ultrasonic coupling material with a gradient acoustic impedance according to claim 1, characterized in that: The particles are admixture 1 whose acoustic impedance is greater than Zp and admixture 2 whose acoustic impedance is less than Zt; admixture 1 belongs to the first oblique splitting structure, and admixture 2 belongs to the second oblique splitting structure.

6. The anti-transmission ultrasonic coupling material with a gradient acoustic impedance according to claim 1, characterized in that: The shape of the wedge structure is an isosceles triangle, and the bottom width W is less than 1 / 4 of the wavelength of the sound wave corresponding to the center frequency of the ultrasonic transducer in the base material.

7. An ultrasonic transducer action device based on the acoustic impedance gradient anti-transmission ultrasonic coupling material according to any one of claims 1 to 6, characterized in that: include: The piezoelectric material is used to emit ultrasonic waves; the anti-reflection ultrasonic coupling material with a gradual acoustic impedance is tightly fitted between the piezoelectric material of the ultrasonic transducer and the object to be measured, so as to achieve a gradual transition of the acoustic impedance; the ultrasonic transducer action device can significantly improve its ultrasonic transmission ability through the anti-reflection ultrasonic coupling material with a gradual acoustic impedance.

8. The ultrasonic transducer action device according to claim 7, characterized in that: The ultrasonic transducer is a strip-shaped monomer or strip-shaped array transducer, and the transmission frequency, power and pulse parameters are tuned by an external control system.

9. A method for preparing an anti-transmission ultrasonic coupling material with a gradient acoustic impedance as claimed in any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: (1) Calculate the acoustic impedance of the first wedge structure and the second wedge structure and the corresponding particle content ratio based on the acoustic impedance of the piezoelectric material and the acoustic impedance of the object to be tested; (2) mixing the base material and the granular material 1 to form a first oblique split structure preparation material, and bonding the first oblique split structure preparation material to the emitting surface of the piezoelectric material of the ultrasonic transducer through mold casting or prefabrication into a layered process to obtain a first oblique split structure quasi-structure; (3) performing laser etching layer by layer on the first oblique-wedge structure quasi-structure to obtain a first oblique-wedge structure; (4) The base material and the particle 2 are mixed to form a second oblique wedge structure preparation material, and the second oblique wedge structure preparation material is loaded into the gap of the first oblique wedge structure through a mold casting process, and then solidified to form a complete acoustic impedance gradient anti-reflection ultrasonic coupling material.

Images