A single / dual frequency array transducer for sound field and focal volume multiplexing

Abstract

The application discloses a single / dual-frequency array transducer for sound field and focal volume multiple regulation, which comprises a transducer shell, one end of the transducer shell is provided with a prismatic baffle, the surface of the prismatic baffle is provided with a multi-array piezoelectric layer, the multi-array piezoelectric layer is provided with variable sound-transparent rubber, the projection surface of the multi-array piezoelectric layer is a circle, the projection surface is divided into three concentric circular rings, and the three concentric circular rings are arranged in the form of a single / dual-frequency curved surface split array with m+n+k, the projection surface of the m, n and k arrays is the three concentric circular rings, different resonance frequencies are obtained by driving different arrays, and due to the single / dual-frequency curved surface split array arrangement mode, the application provides a split array phase regulation and focusing vortex topological charge regulation mode for changing the size of a sound field focal volume, a multiple vortex sound field regulation mode for force field control and a dual-frequency split array and vortex regulation mode for cavitation intensity and distribution efficiency, and the mode has high cavitation activity intensity, easy inertial cavitation and fast temperature rise.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic transducer technology, specifically to a single / dual frequency array transducer for multiple modulation of sound field and focal volume. Background Technology

[0002] Focused ultrasound therapy, as a non-invasive treatment method, has advantages such as being non-invasive, effective, safe, allowing for rapid recovery, and causing no radiation damage. Low-to-medium intensity focused ultrasound (LTI) therapy utilizes the mechanical vibration of ultrasound waves to induce movement of substances within tissue cells. Through a warming effect, it promotes blood circulation, accelerates metabolism, reduces muscle and connective tissue tension to decrease nerve excitability, and, combined with cavitation, alters cell function, enhances vascular permeability, and aids patient recovery, achieving the therapeutic goal. Therefore, LTI is widely used in pain relief, musculoskeletal therapy, tumor treatment, blood-brain barrier opening, and neuromodulation.

[0003] Common focused ultrasound (FUS) transducers are single-frequency. However, at the same acoustic power, dual-frequency FUS transducers exhibit greater cavitation activity and are more prone to inertial cavitation than single-frequency transducers, significantly increasing temperature rise, shortening treatment time, and improving treatment efficiency. Currently, commercially available dual-frequency FUS transducers are simply combinations of two single-frequency FUS transducers with different frequencies. Experimental research has explored achieving dual-frequency FUS by superimposing excitation signals to obtain new frequencies, and by designing two concentric concentric array elements to create a dual-frequency confocal concave spherical FUS transducer. Achieving dual-frequency focusing through excitation signal superposition or the combination of multiple confocal transducers requires a multifunction generator and power amplifier, significantly increasing costs. Structurally, this approach cannot be applied to multi-element transducers. To achieve structural integration of dual-frequency FUS transducers, some research has proposed mechanically bonding two layers of piezoelectric ceramic materials and designing the thickness of the excitation and matching layers to achieve near-identical fundamental frequencies under two different excitations. However, this approach is technically challenging, has low precision, and cannot achieve standardized quantitative results. Summary of the Invention

[0004] The purpose of this invention is to provide a single / dual frequency array transducer for multiple control of sound field and focal volume, so as to overcome the problems of low cavitation activity intensity, difficulty in inertial cavitation, and slow temperature rise in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A single / dual frequency array transducer for multiple modulation of sound field and focal volume includes a transducer housing, a prismatic baffle is provided at one end of the transducer housing, a multi-element piezoelectric layer is provided on the surface of the prismatic baffle, and a variable sound-permeable rubber is provided on the multi-element piezoelectric layer.

[0007] The projection surface of the multi-element piezoelectric layer is a circle, which is divided into three concentric rings and arranged in the form of m+n+k single-frequency / dual-frequency curved surface split array. The projection surfaces of the m, n and k arrays are three concentric rings, where the number of m, n and k arrays are all integers.

[0008] The arrangement of single-frequency / dual-frequency curved surface split arrays includes cutting and integrating three ring structures of m, n, and k using self-focusing concave piezoelectric material, ensuring that the curvature radii of the m, n, and k arrays are consistent, or selecting planar piezoelectric material, where the projection line segments of all array elements in the m and n arrays are chords of circles with radius R, and the curvature radii of the corresponding surfaces of the m, n, and k arrays are consistent.

[0009] Preferably, the multi-element piezoelectric layer uses PZT-4 piezoelectric ceramic or PZT-8 piezoelectric ceramic.

[0010] Preferably, the thickness of the PZT-4 piezoelectric ceramic or the PZT-8 piezoelectric ceramic is less than 3 mm.

[0011] Preferably, the end of the transducer housing away from the prismatic baffle can be held by hand or used in conjunction with a robotic arm.

[0012] Preferably, the m array is the fundamental frequency, the n array is the multiplier frequency, and the k array is the dual frequency.

[0013] Preferably, the individual split arrays of the multi-element piezoelectric layer are closely arranged in an 8+4+4 or 8+4+1 configuration.

[0014] Preferably, the lower surface of the multi-element piezoelectric layer is provided with positive and negative leads, and each split array is matched with a power amplifier board. Different resonant frequencies are obtained by driving the m and n arrays separately or by driving the m and n arrays simultaneously.

[0015] Preferably, the sound-permeable rubber material of the deformable sound-permeable rubber layer is natural rubber.

[0016] Preferably, castor oil is filled between the multi-element piezoelectric layer and the deformable acoustically permeable rubber.

[0017] Preferably, an organic electrical connector is provided inside the transducer housing.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a single / dual-frequency array transducer for multiple modulation of sound field and focal volume, including a transducer shell, a prismatic baffle at one end of the transducer shell, a multi-element piezoelectric layer on the surface of the prismatic baffle, a variable sound-transmitting rubber on the multi-element piezoelectric layer, and a circular projection surface of the multi-element piezoelectric layer, which is divided into three concentric rings and arranged in a single / dual-frequency curved surface split array form of m+n+k. The projection surfaces of the m, n, and k arrays are the three concentric rings. By driving different arrays, different resonant frequencies can be obtained. At the same time, due to the single / dual-frequency curved surface split array arrangement, self-convergence is achieved. The concave piezoelectric material is cut and integrated into a structure of three rings, m, n, and k, ensuring that the curvature radii of the m, n, and k arrays are consistent to achieve confocalization. Alternatively, planar piezoelectric material can be selected, where the projection line segments of all array elements in the m and n arrays are chords of circles with radius R, and the curvature radii of the corresponding surfaces of the m, n, and k arrays are consistent to achieve confocalization. This provides a split array phase control and focusing vortex topology charge control method for changing the size of the focal domain of the sound field, a multi-vortex sound field control method for force field manipulation, and a dual-frequency split array and vortex control method for enhancing cavitation intensity and distribution. Such methods can enhance the intensity of cavitation activity, make inertial cavitation easier to occur, and increase temperature rapidly.

[0019] Furthermore, the sound-permeable rubber material of the deformable sound-permeable rubber layer is natural rubber, which has good sound transmission effect. Natural rubber is also effective in resisting castor oil. At the same time, the use of natural rubber gives the deformable sound-permeable rubber layer good deformation ability, which can fit closely to the body surface and is suitable for use in different parts of the body.

[0020] Furthermore, the multi-element piezoelectric layer uses PZT-4 piezoelectric ceramic or PZT-8 piezoelectric ceramic as raw materials, which has the advantages of strong and stable piezoelectric properties, high Curie temperature, large anisotropy and small dielectric constant.

[0021] Furthermore, the end of the transducer housing away from the prismatic baffle can be held by hand, which makes it more flexible to operate and more versatile in application scenarios compared to the large size and limited application scenarios of previous focused ultrasound therapy transducers. It can also be used in conjunction with a robotic arm to make up for the lack of manpower. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a single / dual frequency array transducer structure for multiple modulation of sound field and focal volume according to the present invention.

[0023] Figure 2 This is a schematic diagram of a single / dual frequency array transducer for multiple control of sound field and focal volume of the present invention, which adopts a multi-element piezoelectric layer m+n+k and a rear prismatic baffle structure using a self-focusing concave piezoelectric material;

[0024] Figure 3 This is a schematic diagram of a single / dual frequency array transducer for multiple modulation of sound field and focal volume of the present invention, which adopts a multi-element piezoelectric layer m+n+k of planar piezoelectric material and a rear prismatic baffle structure.

[0025] Figure 4 This is a schematic diagram of the cross-section of a multi-element piezoelectric layer m, n, and k array of a single / dual-frequency array transducer for multiple modulation of sound field and focal volume, according to the present invention, with the projection of the array as a chord of radius R.

[0026] Figure 5 This is a schematic diagram of the multi-element piezoelectric layer arrangement of a single / dual frequency array transducer for multiple modulation of sound field and focal volume according to the present invention, which uses planar piezoelectric material, where a is 8+4+1 and b is 8+4+4.

[0027] Figure 6 This is a schematic diagram of the feedback control process of a single / dual frequency array transducer for multiple modulation of sound field and focal volume according to the present invention.

[0028] Figure 7 This is a simulation diagram of the focusing transverse sound field of a single / dual frequency array transducer with a frequency of 800kHz for multiple modulation of sound field and focal volume according to the present invention.

[0029] Figure 8 This is a simulation diagram of a single / dual frequency array transducer with a frequency of 800kHz, a topological charge of 1, and a phase difference of pi / 4 between adjacent array elements for multiple control of sound field and focal volume according to the present invention.

[0030] Figure 9 This is a simulation diagram of a focused transverse sound field using a single / dual frequency array transducer with a frequency of 800kHz, a topological charge of 2, and a phase difference of pi / 2 between adjacent array elements, for multiple modulation of sound field and focal volume.

[0031] Among them, 1-multi-element piezoelectric layer, 2-deformable sound-permeable rubber, 3-prismatic baffle, 4-transducer shell. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0033] like Figure 1As shown, this invention provides a single / dual-frequency array transducer for multiple modulations of sound field and focal volume. By optimizing the arrangement of individual array elements in the piezoelectric layer of the transducer, a single / dual-frequency array curved surface transducer for dual modulation of sound field and focal volume is designed. Different frequencies are obtained by driving a single array or simultaneously driving all arrays, thereby changing the sound pressure and cavitation intensity. The phase difference between adjacent array elements of the designed transducer array is adjustable, controlling whether vortex sound fields are generated, and changing the magnitude of the topological charge to change the magnitude of the sound radiation force and the size of the focal volume. In addition, the designed transducer can also be used in conjunction with a receiving transducer, and through a feedback control network, real-time monitoring and adjustment of the amplitude and phase of the sound field can be achieved. Considering operational flexibility, the transducer designed in this invention can be used manually or in conjunction with a robotic arm to compensate for the lack of human resources.

[0034] The transducer structure includes a multi-element piezoelectric layer, deformable acoustically permeable rubber and coupling medium, a prismatic baffle, and a transducer shell. Organic electrical connectors are installed inside the transducer shell. The transducer shell is handheld, which is different from the large size and limited application scenarios of previous focused ultrasound therapy transducers. It is more flexible in operation and can be used in various scenarios. It can also be used in combination with a robotic arm to make up for the lack of manpower. The multi-element piezoelectric layer 1 is placed on the upper surface of the prismatic baffle 3, and the positive and negative leads of the multi-element piezoelectric layer 1 are placed on the lower surface. The prismatic baffle has a hollowed-out design in the middle to facilitate the connection of the leads.

[0035] In terms of material selection, PZT piezoelectric ceramics have strong and stable piezoelectric properties, high Curie temperature, large anisotropy, and small dielectric constant. PZT-4 or PZT-8 piezoelectric ceramics can be selected for the multi-element piezoelectric layer 1. PZT-4 and PZT-8 have strong depolarization ability and low dielectric loss under high voltage drive, making them more suitable for deep immersion acoustic sensors with a thickness of less than 3mm.

[0036] The projection surface of the multi-element piezoelectric layer is a circle, divided into three concentric rings, arranged in the form of a single-frequency / dual-frequency curved surface split array of m+n+k (m, n, k∈Z+). The projection surfaces of the m, n, and k arrays are the three concentric rings.

[0037] In terms of structural selection, the multi-element piezoelectric layer can either use a self-focusing concave piezoelectric material to cut and integrate it into a structure of three rings, m, n, and k, ensuring that the curvature radii of the m, n, and k arrays are consistent and achieving confocalization; or it can use a planar piezoelectric material, in which the projection line segments of all elements in the m and n arrays are chords of circles with radius R, so that the curvature radii of the surfaces corresponding to the m and n arrays are consistent and achieving confocalization.

[0038] The individual split arrays of the multi-element piezoelectric layer are closely arranged, and the arrangement can be 8+4+4 or 8+4+1.

[0039] There are multiple ways to select the frequency of a multi-element piezoelectric layer array. The options include m array as the fundamental frequency, n array as a multiplier frequency, and k array as a dual frequency.

[0040] The positive and negative leads of the multi-element piezoelectric layer are placed on the lower surface. Each split array is matched with a power amplifier board. Different resonant frequencies are obtained by driving the m and n arrays separately or driving the m and n arrays simultaneously. When the m and n arrays are driven simultaneously, the sound pressure is enhanced and the cavitation is enhanced.

[0041] By changing the phase difference between adjacent elements in a single array within a multi-element piezoelectric layer (the phase difference is adjustable), the formation of vortices and the magnitude of the topological charge can be controlled, thereby altering the magnitude of the acoustic radiation force and the focal range.

[0042] The k-array of multi-element piezoelectric layers can serve as both a therapeutic transducer array and a broadband receiving transducer. When used as a broadband receiving transducer, it has a backing. It can receive both subharmonic signals and high-frequency broadband noise. After data processing, it can characterize steady-state cavitation dose and inertial cavitation dose. Real-time monitoring and adjustment of the amplitude and phase of the sound field can be achieved through a feedback control network.

[0043] The deformable sound-permeable rubber layer is made of NR rubber, with a sound transmission coefficient T > 96% at 5–55 kHz. NR is effectively resistant to castor oil, which is then used to fill the space between the transducer piezoelectric layer and the sound-permeable rubber. The deformable sound-permeable rubber layer has good deformation capabilities, allowing it to fit tightly to the body surface and adapt to use in different locations.

[0044] like Figure 2 and Figure 3 As shown, the projection surface of the multi-element piezoelectric layer is a circle, divided into three concentric rings, arranged in a single-frequency / dual-frequency curved surface split array form of m+n+k (m, n, k∈Z+). The projection surfaces of the m, n, and k arrays are the three concentric rings. Furthermore, in terms of structural selection, the multi-element piezoelectric layer can be constructed by cutting a self-focusing concave piezoelectric material and then integrating it into a structure of three rings (m, n, and k), as shown in the example. Figure 2 As shown, ensuring that the radii of curvature of arrays m, n, and k are consistent achieves confocal focusing; alternatively, planar piezoelectric materials can be selected, such as... Figure 3 As shown, the projection line segments of all array elements in arrays m and n are chords of circles with radius R, such as... Figure 4 As shown, this ensures that the radii of curvature of the surfaces corresponding to the m and n arrays are consistent, thus achieving confocal focusing.

[0045] The individual splitting matrices are arranged closely together, in the following manner: Figure 5 As shown, the array can be, but is not limited to, 8+8+4 or 8+8+1. The frequency of the multi-element piezoelectric layer array can be selected in various ways, including m-array as the fundamental frequency, n-array as a multiplier frequency, and k-array as a dual-frequency array.

[0046] Each split array is matched with a power amplifier board. During driving, either the m or n array can be driven individually, or both m and n arrays can be driven simultaneously. The same transducer can achieve three resonant frequencies. When driving both m and n arrays simultaneously, sound pressure and cavitation are enhanced. By changing the phase difference between adjacent elements in a single array within the multi-element piezoelectric layer (the phase difference is adjustable), the formation of vortices and the magnitude of the topological charge can be controlled, thereby altering the magnitude of the acoustic radiation force and the focal region. The invented transducer is suitable for processing different targets, expanding its application range.

[0047] The k-array of the multi-element piezoelectric layer can be either one of the arrays of therapeutic transducers or a broadband receiving transducer. When it is a broadband receiving transducer, it has a backing. It can receive both subharmonic signals and high-frequency broadband noise. After data processing, it can characterize steady-state cavitation dose and inertial cavitation dose, such as... Figure 6 As shown, the amplitude and phase of the sound field are monitored and adjusted in real time through a feedback control network.

[0048] When the phase difference between adjacent elements of the m-array of the multi-element piezoelectric layer is 0 and the topological charge is 0, the transducer is a non-vortex focusing ultrasonic transducer, and the simulation results of its transverse sound field are as follows: Figure 7 As shown, the sound pressure is strongest at the focal point and gradually decreases towards the periphery of the focal region. When the m-array topological charge of the multi-element piezoelectric layer is 1, the transducer is a vortex-focusing ultrasonic transducer, and the simulation results of its transverse sound field are as follows. Figure 8 As shown, the sound pressure level in the focal center region is 0. Figure 9 The topological load is set to 2, and the remaining simulation parameters are the same as those in the simulation. Figure 8 The results are consistent. Comparing the two sets of results, it can be found that when other parameters remain the same, the peak sound pressure decreases with increasing topological charge, while the range of the acoustic well increases with increasing topological charge, resulting in a larger acoustic manipulation range. By changing the magnitude of the topological charge, dual control over the sound field and focal zone volume can be achieved.

[0049] The transducer housing is handheld and can also be used in conjunction with a robotic arm.

[0050] The present invention has the following advantages:

[0051] a. By optimizing the arrangement of the piezoelectric layer split array of the transducer, in terms of structural selection, either a self-focusing concave piezoelectric material can be cut and then integrated into a structure of three rings, m, n and k, to ensure that the curvature radii of the m, n and k arrays are consistent, thus achieving confocalization; or a planar piezoelectric material can be selected, in which the projection line segments of all array elements in the m and n arrays are chords of circles with radius R, so that the curvature radii of the surfaces corresponding to the m and n arrays are consistent, thus achieving confocalization.

[0052] b. By driving the m and n arrays separately or simultaneously, different resonant frequencies can be obtained, enabling the transducer to operate at multiple operating frequencies, making it suitable for different target processing and expanding its application range.

[0053] c. By changing the phase difference between adjacent elements in a single array within a multi-element piezoelectric layer, the phase difference can be adjusted to control whether vortices are formed and to change the topological charge, thus facilitating changes in the magnitude of acoustic radiation force and focal size.

[0054] d. The receiving transducer is dual-frequency. After data processing, steady-state cavitation and inertial cavitation doses can be obtained simultaneously. Combined with the feedback control network, the amplitude and phase of the sound field can be monitored and adjusted in real time.

[0055] e. The transmitting and receiving transducers are integrated, making operation more flexible and convenient.

[0056] f. The transducer is equipped with deformable sound-permeable rubber, which makes it fit more closely to the test surface.

[0057] g. The transducer housing is handheld, which is different from the large size and limited application scenarios of previous focused ultrasound therapy transducers. It is more flexible in operation and can be used in various scenarios. It can also be used in conjunction with a robotic arm to make up for the lack of manpower.

[0058] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art, guided by the specification, can make many other modifications without departing from the scope of the claims of the present invention, and all of these modifications are within the scope of protection of the present invention.

Claims

1. A single / dual frequency array transducer for sound field and focal volume multiplexing, characterized by, The transducer shell (4) is provided with a prismatic baffle (3) at one end, and the surface of the prismatic baffle (3) is provided with a multi-element piezoelectric layer (1), and the multi-element piezoelectric layer (1) is provided with a deformable sound-transparent rubber (2); The projection surface of the multi-element piezoelectric layer (1) is a circle, and the projection surface is divided into three concentric circular rings arranged in the form of a single / dual-frequency curved surface split array of m+n+k, and the projection surfaces of the m, n and k arrays are three concentric circular rings, wherein m, n and k are integers. The single / dual-frequency curved surface split array arrangement includes cutting a self-focusing concave piezoelectric material and integrating it into the structure of three circular rings of m, n and k, to ensure that the curvature radii of the m, n and k arrays are consistent, or selecting a planar piezoelectric material, wherein the projection line segments of all elements in the m and n arrays are chords of a circle with a radius R, and the curvature radii of the curved surfaces corresponding to the m, n and k arrays are consistent. The single split array of the multi-element piezoelectric layer (1) is closely arranged in the form of 8+4+4 or 8+4+1. The m array is a fundamental frequency, the n array is a multiple frequency, and the k array is a dual frequency.

2. A single / dual frequency array transducer for multi-regulation of sound field and focal volume according to claim 1, characterized in that, The multi-element piezoelectric layer (1) uses PZT-4 piezoelectric ceramic or PZT-8 piezoelectric ceramic.

3. A single / dual frequency array transducer for multi-regulation of sound field and focal volume according to claim 2, characterized in that, The thickness of the PZT-4 piezoelectric ceramic or PZT-8 piezoelectric ceramic is less than 3mm.

4. A single / dual frequency array transducer for multi-regulation of sound field and focal volume according to claim 1, characterized in that, The end of the transducer shell (4) away from the prismatic baffle (3) can be handheld or cooperated with a mechanical arm.

5. A single / dual frequency array transducer for multi-regulation of sound field and focal volume according to claim 1, characterized in that, The lower surface of the multi-element piezoelectric layer (1) is provided with positive and negative lead wires, and each split array is matched with a power amplifier board to obtain different resonant frequencies by driving the m and n arrays respectively or simultaneously.

6. A single / dual frequency array transducer for multi-regulation of sound field and focal volume according to claim 1, characterized in that, The sound-transparent rubber material of the deformable sound-transparent rubber (2) is natural rubber.

7. A single / dual frequency array transducer for multi-regulation of sound field and focal volume according to claim 1, characterized in that, Castor oil is filled between the multi-element piezoelectric layer (1) and the deformable sound-transparent rubber (2).

8. The single / dual-frequency array transducer for multi-control of sound field and focal volume according to claim 1, wherein the transducer shell (4) is internally provided with a mechanical and electrical connector.

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