Development of high intensity focused ultrasound transducer

In this section, two kinds of piezoelectric ceramics composite materialswith a center frequency of around 50 MHz are prepared to prepare two kinds of poly. Focused ultrasonic transducers in the form of a focal point are spherical focus and cylindrical line focus, respectively. The schematic diagram of the ultrasonic transducer is as follows:

     The basic structure of the high focused ultrasound transducer is divided into piezoelectric material, acoustic matching layer, acoustic backing layer, outer casing and wires, etc. The structure and composition of each part are shown in the figure. According to the preparation and characteristics of the l-3 type piezoelectric composite material,In this paper, a piezoelectric composite material with a volume fraction is 35.84%. piezoelectric ceramic phase material was prepared by cutting and filling method. wherein the piezoelectric ceramic column has a square cross section with a column width of 36.03 um and a thickness d of 36.52 um.

The slit width is 24.14 um. The fabricated piezoelectric composite material is shaped by a certain process to form spherical and cylindrical surfaces are used to focus the sound waves, then the backing material and bonding electrodes and packages are applied.The finished spherical point high intensity focused ultrasound is 0.6mm '0.6mm, and the depth of focus is 10mm;The size of the cylindrical line focused ultrasound transducer is 0.5mm X 0.6mm, and the axial depth of focus is 5.smm.

After testing, when the transducer resonates, the series resonant frequency is the series resonant frequency artificially 45.968MHz, the parallel resonant frequency is a few 60·253 MHz, and the center frequency fc is 53.111 MHz.

It can be seen that after the acoustic matching layer is matched, the acoustic waveform is obviously improved, and the number of sound waves is oscillated.Decreasing the time of pulse width is reduced, and the bandwidth in the frequency domain is increased.

     Performing a sound field scan on the inductive ultrasonic proximity sensors is the experiment can be used to determine the ultrasonic wave emitted by the transducer.The distribution of sound pressure in space. In turn, the focus position of the sound wave and the size of the focus can be determined, and the performance of the transducer has important reference value. This section uses the laboratory's three-dimensional sound field scanning system to make the spherical surface.The three-dimensional sound field of the point-focusing and cylindrical line-focusing ultrasound transducers was scanned using a diameter.0.2mm high-precision hydrophone tester.

After scanning the axial sound pressure, it can be concluded that the spherical spot focused ultrasonic transducer has a depth of focus of 5.3 mm.

Spherical point focused ultrasound transducer has the sound field test