CN1669672A - Piezoelectric type multi array element high intensity focusing ultrasonic transducer and focusing method - Google Patents

Abstract

The invention relates to a piezoelectric focusing ultrasonic transducer, which comprises a concave spherical lightening housing (1), a unit focusing energy converter (2), an end cap (3), a gasket (4), a connector base (5) and an insulating connector base (6). The method uses the polyvalent secondary focusing method to geometrical focus with high intensity. The device can produce the high-intensity focusing ultrasonic with prompt high pressure and temperature effect, and has small focus range and large acoustic pressure, and the system is stable, and it can be widely used in the biology, medical treatment, manufacturing and other technique fields.

Description

Piezoelectric multi-element high-intensity focused ultrasound transducer and focusing method

technical field

The piezoelectric multi-element high-intensity focused ultrasonic transducer and focusing method referred to in the present invention belong to ultrasonic transducers, which can produce high-intensity focused ultrasonic with instantaneous high-temperature and high-pressure effects, and are widely used in biology, medical treatment, manufacturing and other technical fields.

Background technique

By applying pulsed electrical excitation to the piezoelectric transducer, the piezoelectric transducer generates pulsed ultrasonic waves. With proper focusing technology, high-intensity focused ultrasound can be formed in the focused area, which has the characteristics of instantaneous high temperature and high pressure.

At present, the existing ultrasonic focusing methods include: multiple coherent focusing, multiple non-coherent focusing, phase control focusing, unit acoustic lens focusing and concave spherical chip self-focusing, etc. However, considering factors such as the complexity of the manufacturing process and system stability, two methods of acoustic lens focusing and concave spherical wafer self-focusing are often used in use. In comparison, the performance of the above two focusing methods is similar, but the manufacturing process and cost of the latter are much higher than the former.

Through patent literature search, Shanghai Jiaotong University and Wuxi Haiying Electronic Medical System Co., Ltd. jointly applied for the invention patent "Transducer Array for High-Intensity Focused Ultrasound Tumor Therapy" (patent application number: 03129407.3), which consists of a matching layer and piezoelectric ceramics slice composition. The matching layer is a concave spherical thin-shell bowl-shaped sound radiation layer with uniform thickness. All piezoelectric ceramic sheets are glued on the outer surface of the same matching layer. Multiple identical piezoelectric ceramic sheets are used to form a large-aperture common concave Spherical closely mosaic transducer array, with high array focused sound intensity ratio and symmetrical focused sound field characteristics. However, this invention does not take into account the refraction effect of the matching layer on ultrasonic waves, and the acoustic focus of each unit transducer is not on the geometric center of the large-aperture co-concave spherical surface.

The utility model patent "a focused ultrasonic wave source" (patent application number: 01270265.X) declared by Beijing Yuande Biomedical Engineering Co., Ltd. provides a focused ultrasonic wave source, including ultrasonic emitting components for emitting ultrasonic waves and In the focusing part that focuses the emitted ultrasonic wave, the emitted ultrasonic wave is focused by the focusing part and transmitted to the focus in the form of a near spherical wave. The focusing performance of the test is obviously better than that of the existing small aperture angle wave source. However, due to the limitation of the acoustic power of the unit transducer, the intensity of the focused ultrasound is relatively small.

Contents of the invention

Comprehensively considering the demand characteristics of high-intensity focused ultrasound transducers, the purpose of the present invention is to develop a novel piezoelectric multi-element high-intensity focused ultrasound transducer to generate high-intensity focused ultrasound with instantaneous high-temperature and high-pressure effects. It has the advantages of small focal area, large sound pressure, stable system and controllable energy, and can be widely used in biology, medical treatment, manufacturing and other technical fields.

The piezoelectric multi-element high-intensity focused ultrasonic transducer that achieves the above-mentioned goals includes a concave spherical light-weight housing, which can be installed in a plurality of unit focusing transducers (seven in the present invention) that are symmetrically distributed in the concave spherical light-weight housing. If it is used in the medical field, the unit focusing transducer at the center of the concave spherical light shell can be replaced by other testing and positioning components), the end cover is placed on the upper end of the concave spherical light shell, and there is a seal between the two Gasket sealing, piezoceramics are pasted on the back of the acoustic lens to form a unit focusing transducer. The present invention adopts a multi-element secondary focusing method, that is, unit transducers are focused by an acoustic lens, and each unit transducer is installed on the same concave spherical surface to realize secondary geometric focusing.

Combining the respective advantages of unit acoustic lens focusing and multi-element focusing, on this basis, a new type of multi-element high-intensity focused ultrasonic transducer technology is creatively proposed, and the multi-element secondary focusing method is used to avoid the intensity of unit acoustic lens focused ultrasound. Disadvantages of small size and too many multi-focus piezoelectric ceramics. Therefore, the device of the present invention has simple structure, convenient use and low cost.

Description of drawings

Figure 1. Structural schematic diagram of piezoelectric multi-element high-intensity focused ultrasound transducer

Label names in the figure: 1. Concave spherical light shell, 2. Unit focusing transducer, 3. End cover, 4. Gasket, 5. Terminal block, 6. Insulated connection seat

Figure 2 Schematic diagram of concave spherical lightweight shell

Figure 3 Schematic diagram of unit focusing transducer

Label names in the figure: 7. Acoustic lens, 8. Piezoelectric ceramics.

Figure 4 Schematic diagram of the end cover

Figure 5. Schematic diagram of piezoelectric multi-element high-intensity focused ultrasound transducer

Label name in the figure: 9. Piezoelectric multi-element high-intensity focused ultrasonic transducer, 10. High-power ultrasonic power supply

Detailed ways

The concrete structure of the present invention is: as shown in Figure 1, a plurality of unit transducers 2 are housed in the mounting hole of the concave spherical light shell 1, the end cover 3 is placed on the upper end of the concave spherical light shell 1, both Seal with gasket 4 between. The concave spherical light weight shell 1 is shown in Figure 2. On the concave spherical light weight shell 1, the mounting holes for the array unit focusing transducer 2 are designed, and the axes of each hole are at the center of the concave spherical light weight shell. Intersection; according to the empirical calculation formula of the focal length of the acoustic focus:

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them: take the spherical radius R of the concave spherical lightweight shell as the acoustic focusing focal length of the unit focusing transducer 2, r is the concave spherical radius of the acoustic lens 7 in the unit focusing transducer 2, and _C1 is the material of the acoustic lens 7 Internal sound velocity, C ₂ is the internal sound velocity of the ultrasonic transmission medium. C ₁ and C ₂ can be obtained through actual measurement or by consulting relevant manuals.

As shown in Figure 3, the unit focusing transducer is composed of a concave spherical acoustic lens 7 and piezoelectric ceramics pasted on the back plane of the concave spherical acoustic lens. The spherical radius r of the concave spherical surface of the acoustic lens 7 of the unit focusing transducer 2 can be calculated from formula (1), so as to process the concave spherical surface of the acoustic lens 7 . The focusing transducers of each unit are installed in the concave spherical lightweight casing 1, so as to ensure that the pulsed ultrasonic waves emitted by each unit focusing transducer can converge at the geometric center of the concave spherical lightweight casing 1.

The number of unit focusing transducers is determined by the specific dimensions of the unit focusing transducers and the concave spherical lightweight shell, and is designed according to actual needs.

In order to ensure the focusing accuracy, the CNC machining method can be used to process all the unit transducer mounting holes on the concave spherical lightweight shell 1 through one clamping, so as to ensure the position accuracy and cylindricity requirements of each hole.

The acoustic lens 7 of the unit focusing transducer 2 is made of duralumin, which can be processed by numerical control, and through one clamping, it can meet the required surface processing accuracy and quality, and ensure the bonding quality and acoustic focusing effect;

A special bonding process is adopted to ensure the bonding quality of the piezoelectric ceramic 8 and the acoustic lens 7 .

The end cap 3 is shown in FIG. 4 .

Figure 5 is a schematic diagram of the piezoelectric multi-element high-intensity focused ultrasound transducer in use, that is, the high-power ultrasonic power supply 10 is connected to the piezoelectric multi-array high-intensity focused ultrasonic transducer through the terminal block 5 on the end cover 3. The transducer 9 is connected.

Claims (4)

1. A piezoelectric multi-element high-intensity focused ultrasonic transducer, characterized in that: the unit focused transducer (2) is fixed in the concave spherical light shell (1) through a mounting hole, and the piezoelectric ceramic ( 8) It is bonded to the back of the acoustic lens 7 to form a unit energy conversion focusing transducer (2), the end cover (3) is placed on the upper end of the concave spherical light shell (1), the gasket (4) is sealed, and the terminal block ( 5) Located on the end cover (3), the installation and use requirements of the overall transducer can be met by using the insulating connection seat (6). 2. A focusing method for a piezoelectric multi-element high-intensity focused ultrasonic transducer, which is characterized in that a multi-element secondary focusing method is adopted, that is, the unit transducers are focused by an acoustic lens, and each unit transducer is installed on the On the same concave spherical surface, the secondary geometric focus is realized. 3. The piezoelectric multi-element high-intensity focused ultrasonic transducer according to claim 1, characterized in that the radius (R) of the concave spherical surface of the lightweight casing (1) is the same as that of the unit focusing transducer (2 ) The focal lengths (f) of the acoustic focus are equal to meet the geometric focus requirements; 4. The piezoelectric multi-element high-intensity focused ultrasonic transducer according to claim 1 or 3, characterized in that the front of the acoustic lens (7) of the unit focused transducer (2) is a concave spherical surface, and its spherical surface The radius (r) can be given by the empirical formula $R=\frac{r}{1-C_1/C_2}$ Calculated; the back is flat.