Ultrasonic focusing probe

Abstract

The invention discloses an ultrasonic focusing probe. The ultrasonic focusing probe comprises a shell, a piezoelectric wafer, a spherical acoustic lens, a functional layer and a conducting medium, an accommodating space is formed in the shell; the piezoelectric wafer is arranged at the upper part of the accommodating space and is connected with a wire; the spherical acoustic super lens is coaxially arranged below the piezoelectric wafer, and a gap is formed between the spherical acoustic super lens and the piezoelectric wafer; the functional layer is arranged at the lower end of the shell and is constructed into the lower end surface of the shell; and the conductive medium is filled in the accommodating space and wraps the spherical acoustic super lens. According to the ultrasonic focusing probe, the spherical acoustic super lens is adopted, the focus width is narrower, and the transverse resolution of ultrasonic imaging can be improved. The focus energy of the spherical acoustic super lens is larger, and the focusing energy gain reaches more than 20dB, so that the contrast ratio of ultrasonic imaging can be improved. The spherical inner core and the spherical outer shell form a core-shell structure, and the focal length and the focal width of the ultrasonic focusing probe can be changed through the sizes of the spherical inner core and the spherical outer shell.

Description

Technical Field

[0001] The invention belongs to the technical field of ultrasonic detection, and in particular relates to an ultrasonic focusing probe. Background Art

[0002] In ultrasonic imaging, the ultrasonic probe can convert the plane wave generated by the piezoelectric chip into a focused beam, thereby improving the lateral resolution of the imaging. Existing ultrasonic imaging technology mainly uses a focused acoustic lens to focus the beam, such as using sapphire to make an acoustic lens. For a specific piezoelectric chip, by designing the radius of curvature of the lens, a focused beam with a specific focal length, focal width, and focal depth can be achieved. However, although the traditional acoustic lens can focus the beam, it is always limited by diffraction and it is difficult to achieve a sub-wavelength focal width, so it is impossible to further improve the lateral resolution of the ultrasonic microscope.

[0003] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0004] An object of the present invention is to provide an ultrasonic focusing probe which can improve the lateral resolution of ultrasonic imaging.

[0005] In order to achieve the above-mentioned purpose, a technical solution provided by a specific embodiment of the present invention is as follows: an ultrasonic focusing probe, comprising: a shell, a piezoelectric chip, a spherical acoustic lens, a functional layer and a conductive medium. The shell has a containing space inside; the piezoelectric chip is arranged at the upper part of the containing space and is connected with a wire; the spherical acoustic superlens is coaxially arranged below the piezoelectric chip and has a gap between the piezoelectric chip and the spherical acoustic superlens; the functional layer is arranged at the lower end of the shell and is configured as the lower end surface of the shell; the conductive medium is filled in the containing space and wraps the spherical acoustic superlens.

[0006] In one or more embodiments of the present invention, the spherical acoustic metalens comprises: a spherical core, a spherical shell and an adhesive layer. The spherical shell is arranged on the surface of the spherical core and wraps the spherical core; the adhesive layer is arranged between the spherical core and the spherical shell, connecting the spherical core and the spherical shell.

[0007] In one or more embodiments of the present invention, a radius ratio of the spherical inner core to the spherical outer shell is between 0.5-0.95.

[0008] In one or more embodiments of the present invention, the material of the spherical inner core is selected from one of carbon steel, lead and stainless steel.

[0009] In one or more embodiments of the present invention, the material of the spherical shell is selected from one of polystyrene, polyvinyl chloride and polyethylene.

[0010] In one or more embodiments of the present invention, the functional layer is configured as a plane.

[0011] In one or more embodiments of the present invention, the acoustic impedance of the functional layer matches that of the conductive medium; and the functional layer is selected from one of PDMS and rubber.

[0012] In one or more embodiments of the present invention, the conductive medium is selected from one of hydrogel, PDMS, and PDMS added with tungsten powder or aluminum oxide powder.

[0013] In one or more embodiments of the present invention, a backing material is disposed between the piezoelectric wafer and the upper end surface of the housing.

[0014] In one or more embodiments of the present invention, the backing material is selected from one of epoxy resin and a doping material based on epoxy resin.

[0015] Compared with the prior art, the ultrasonic focusing probe of the present invention adopts a spherical acoustic superlens, the width of which is narrower, and can improve the lateral resolution of ultrasonic imaging compared with the traditional ultrasonic lens. In addition, the focal energy of the spherical acoustic superlens is larger, and the energy gain of focusing is more than 20dB, thereby improving the contrast of ultrasonic imaging. The spherical core and the spherical shell form a core-shell structure, and the focal length and focal width of the ultrasonic focusing probe can be changed by the size of the two. In addition, a planar functional layer is provided to prevent bubbles from being generated when the probe is vertically immersed in water, which facilitates the use of the probe. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 is a schematic diagram of an ultrasonic focusing probe according to an embodiment of the present invention;

[0018] Figure 2 This is a diagram showing the internal structure of an ultrasonic focusing probe in one embodiment of the present invention;

[0019] Figure 3 is a sound field diagram of the ultrasonic focusing probe in embodiment 1 of the present invention;

[0020] Figure 4It is a normalized sound intensity map of the ultrasonic focused probe in Example 1 of the present invention.

[0021] Description of main reference numerals:

[0022] 1-shell, 2-piezoelectric chip, 3-spherical acoustic superlens, 31-spherical core, 32-spherical shell, 33-adhesive layer, 4-functional layer, 5-backing material. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0024] like Figure 1-2 As shown, an ultrasonic focusing probe in one embodiment of the present invention includes a shell 1, a piezoelectric chip 2, a spherical lens, a functional layer 4 and a conductive medium. The shell 1 has a containing space inside. The piezoelectric chip 2 is arranged at the upper part of the containing space and is connected with a wire. The piezoelectric chip 2 is used to generate and receive ultrasonic waves. The spherical acoustic superlens 3 is coaxially arranged below the piezoelectric chip 2 and has a gap between the piezoelectric chip 2. The functional layer 4 is arranged at the lower end of the shell 1 and is configured as the lower end surface of the shell 1. The conductive medium is filled in the containing space and wrapped by the spherical acoustic superlens 3.

[0025] The working principle of the ultrasonic focusing probe is as follows: after the piezoelectric chip 2 is powered on, it emits ultrasonic waves to the spherical acoustic superlens 3. The ultrasonic waves are converged by the spherical acoustic superlens 3 and transmitted to the detection object through the functional layer 4 with sound-transmitting function. After the ultrasonic waves are emitted to the detection object, they are transmitted back to the piezoelectric chip 2, and then processed by the external processing equipment to form the corresponding ultrasonic image.

[0026] When sound waves interact with the spherical acoustic superlens, a subwavelength focusing effect can be achieved through multiple sound wave scattering, an effect that can break through the diffraction limit of traditional ultrasound probes. The "phonon jet" that can be formed by the spherical acoustic superlens when sound waves pass through it has characteristic parameters (such as length, width, and maximum pressure) similar to photon jets in optics. Although there are essential differences in the physical properties of sound waves and electromagnetic waves, the feasibility of phonon jet formation has been confirmed by using scalar methods in the field of acoustics to simulate the sound wave scattering behavior on the spherical acoustic superlens.

[0027] Spherical acoustic superlenses made of polymer materials can achieve super-focusing of sound waves, that is, a focusing effect exceeding the diffraction limit is produced in the near field of the shadow area of ​​the sphere. This super-focused sound beam is not easily affected by diffraction during propagation. Traditional methods improve resolution by increasing the frequency, but this reduces the penetration depth of ultrasound and increases costs. In contrast, spherical acoustic superlenses 3 are used in ultrasonic imaging systems to overcome the spatial resolution limitations of traditional ultrasonic imaging.

[0028] In the above embodiment, the ultrasonic focusing probe uses a spherical acoustic superlens 3, whose focal width is narrower, and can improve the lateral resolution of ultrasonic imaging compared with a traditional ultrasonic lens. In addition, the focal energy of the spherical acoustic superlens 3 is larger, and the focused energy gain is more than 20 dB, thereby improving the contrast of ultrasonic imaging. In addition, the spherical acoustic superlens 3 can also simplify the overall system structure.

[0029] In one embodiment, if Figure 2 As shown, the spherical acoustic superlens 3 includes a spherical core 31, a spherical shell 32 and an adhesive layer 33. The spherical shell 32 is arranged on the surface of the spherical core 31 and wraps the spherical core 31. The spherical core 31 and the spherical shell 32 are arranged in this way to form a core-shell structure. By adjusting the size of the spherical core 31 and the spherical shell 32, the focal length and focal width of the ultrasonic focusing probe can be changed. An adhesive layer 33 is also arranged between the spherical core 31 and the spherical shell 32 to connect the spherical core 31 and the spherical shell 32.

[0030] Furthermore, the radius ratio of the spherical inner core 31 to the spherical outer shell 32 is between 0.5-0.95 to ensure the imaging effect of the ultrasonic focusing probe.

[0031] The material of the spherical inner core 31 is selected from one of carbon steel, lead and stainless steel. These materials can reduce the attenuation of ultrasonic waves in the spherical acoustic superlens. The material of the spherical outer shell 32 is selected from one of polystyrene, polyvinyl chloride and polyethylene.

[0032] In one embodiment, the functional layer 4 is used to match the acoustic impedance and protect the spherical acoustic superlens 3. For example, the functional layer 4 can be made of one of PDMS and rubber, and the PDMS and rubber can be doped with tungsten powder, aluminum oxide and other powders to adjust the acoustic impedance of the functional layer 4.

[0033] The acoustic impedance of the functional layer 4 matches the acoustic impedance of the conducting medium so that it can efficiently conduct ultrasound. Furthermore, the functional layer 4 is constructed as a plane, so that the end face of the ultrasound probe is a plane rather than a curved surface. Compared with the curved probe, the flat probe can avoid the generation of bubbles when it is vertically immersed in water, and there is no need to deliberately remove the bubbles on the end face, which is convenient for use.

[0034] In one embodiment, the remaining portion of the accommodation space in the housing 1 is filled with a conductive medium. The conductive medium is selected from one of hydrogel, PDMS, and PDMS with tungsten powder / aluminum oxide powder added. The conductive medium improves the efficiency of ultrasonic wave conduction and reduces the loss of ultrasonic wave during conduction.

[0035] In one embodiment, a backing material 5 is further provided between the piezoelectric chip 2 and the upper end surface of the housing 1. The backing material 5 is selected from one of epoxy resin and a doped material based on epoxy resin. The backing material 5 is fixed to the back of the piezoelectric chip 2 and connected thereto. The backing material 5 can be used to control the frequency and pulse response of the ultrasonic focusing probe. The backing material 5 can use its own damping and sound absorption characteristics to terminate the resonance process of the piezoelectric chip 2 as soon as possible, so as to increase the bandwidth to obtain a narrow pulse and improve the axial resolution of the ultrasonic focusing probe.

[0036] The present invention is further described below in conjunction with embodiments and comparative examples.

[0037] Example 1

[0038] Spherical acoustic superlens 3: The material of the spherical core 31 is selected from carbon steel. The material of the spherical shell 32 is selected from polystyrene. The radius of the spherical core 31 is 4.1 mm, and the radius of the spherical shell 32 is 6.8 mm; the radius ratio of the spherical core 31 to the spherical shell 32 is 0.6.

[0039] Functional layer 4: PDMS.

[0040] Conductive medium: hydrogel.

[0041] as follows Figure 3 and Figure 4 As shown, the probe center frequency of the ultrasonic focusing probe is 1.95 MHz, the focal width is 0.51λ, the resolution reaches 0.36λ, and the signal gain is 23 dB.

[0042] It can be seen from the above embodiments that the focal width of the ultrasonic focusing probe of the present invention is narrower, which is better than the focusing effect of a traditional lens and can improve the lateral resolution of ultrasonic microscope imaging.

[0043] In summary, the ultrasonic focusing probe adopts a spherical acoustic superlens 3, whose focal width is narrower, and can improve the lateral resolution of ultrasonic imaging compared with a traditional ultrasonic lens. In addition, the focal energy of the spherical acoustic superlens 3 is larger, and the focused energy gain is more than 20 dB, thereby improving the contrast of ultrasonic imaging. The spherical inner core 31 and the spherical outer shell 32 form a core-shell structure. Through the size of the two, the focal length and focal width of the ultrasonic focusing probe can be changed to adjust the imaging performance of the ultrasonic focusing probe. In addition, a planar functional layer 4 is provided to avoid bubbles in the probe and facilitate the use of the probe.

[0044] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0045] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An ultrasonic focused probe, characterized in that: include: A housing having an accommodating space therein; A piezoelectric chip is arranged at the upper part of the accommodating space and is connected with a wire; A spherical acoustic superlens is coaxially disposed below the piezoelectric wafer and spaced apart from the piezoelectric wafer; A functional layer, disposed at the lower end of the shell and configured as the lower end surface of the shell; and A conductive medium is filled in the accommodating space and wraps the spherical acoustic superlens.

2. The ultrasonic focusing probe according to claim 1, characterized in that: The spherical acoustic superlens comprises: Spherical core; A spherical shell, disposed on the surface of the spherical core and wrapping the spherical core; and The adhesive layer is arranged between the spherical core and the spherical shell to connect the spherical core and the spherical shell.

3. The ultrasonic focusing probe according to claim 2, characterized in that: The radius ratio of the spherical inner core to the spherical outer shell is between 0.5 and 0.

95.

4. The ultrasonic focusing probe according to claim 2, characterized in that: The material of the spherical inner core is selected from one of carbon steel, lead and stainless steel.

5. The ultrasonic focusing probe according to claim 1, characterized in that: The material of the spherical shell is selected from one of polystyrene, polyvinyl chloride and polyethylene.

6. The ultrasonic focusing probe according to claim 1, characterized in that: The functional layer is configured as a plane.

7. The ultrasonic focusing probe according to claim 1, characterized in that: The acoustic impedance of the functional layer matches the acoustic impedance of the conductive medium; and the functional layer is selected from one of PDMS and rubber.

8. The ultrasonic focused probe according to claim 1, characterized in that: The conductive medium is selected from one of hydrogel, PDMS and PDMS added with tungsten powder / aluminum oxide powder.

9. The ultrasonic focusing probe according to claim 1, characterized in that: A backing material is arranged between the piezoelectric wafer and the upper end surface of the shell.

10. The ultrasonic focusing probe according to claim 9, characterized in that: The backing material is selected from one of epoxy resin and a doping material based on epoxy resin.

Images