Array structure of HIFU piezo ceramic

In this section, we designed a HIFU piezo ceramic treatment array with 125 channels and the array column structure was simulated by sound field, and the theoretical analysis of the array was continuous with the excitation signal at the frequency 2MHz. the result of single-point focusing under the string signal shows that the array can achieve single-point deflection focusing, maximum deflection range is 12 mm3, the focal point of single physical focusing is 1.5 and 7.5mm3. In addition, we have also designed a manufacturing solution for the probe package structure, and built the corresponding package structure and manufacturing level station. The content of the program is to fix the array elements by mechanical fixing and utilize 3D rapid prototyping technology. By the CNC technology, electroplating and semi-automatic lathe machining methods for complex structures and high dimensional accuracy.array structure manufacturing process of HIFU piezo transducer is the use of a combination of openscad and MATLAB Programming to build a design platform for the package structure. The value of the platform lies in the subsequent treatment of the HIFU probe.The development provides a fast, low-cost, and operative manufacturing method.

After the performance test of the 125-element therapeutic probe, after the piezoelectric material HIFU piezo treatment probe is manufactured, its performance needs to be tested to judge its performance. The measurement methods we use electrical performance test and acoustic performance test. In the electrical performance test, the resonance frequency of probe has impedance value, anti-resonance frequency and other parameters can be observed to observe the electrical consistency between the array elements and provide strong evidence for the subsequent electrical impedance. In the acoustic performance test, the sound field characteristics such as the optimal working frequency, focal length, and deflection effect of the probe can be determined. The piezoelectric vibrator is connected to the circuit, and the frequency of the excitation source signal is changed. The curve the impedance modulus of the piezoelectric vibrator as a function of frequency is as shown in the right figure. According to the resonance theory, the piezoelectric vibrator has a frequency in which the signal voltage and the current are in the phase near the minimum impedance frequency claw. This frequency is the resonance frequency of the piezoelectric vibrator. Similarly, in the vicinity of the maximum impedance frequency , there is the frequency at which the signal voltage is opposite to the current phase, which is the resonant frequency of HIFU piezo vibration sensor.

The electrical characteristics of the piezoelectric vibrator at resonance can be equivalent to the LC series-parallel loop shown in the Figure , and the equivalent impedance expression of the piezoelectric vibrator is impedance measurement of the probe, the impedance analyzer is a powerful device for electronic component design and circuit equivalent impedance measurement. In the electrical performance test of the ultrasonic probe, the Agilent 4294A precision impedance analyzer (test band range: 40 Hz to 110 MHz; basic impedance accuracy of 0.08%) was used for electrical performance testing. According to different application conditions, the corresponding test parameters are selected. The impedance phase test commonly used in ultrasonic probes is taken as an example. The specific test operations are as follows:

(1) The impedance analyzer is preheated and initializes the measurement parameters;
(2) Determining the test probe is properly connected to the test port;
(3) In the test module, selecting test parameters such as a Z-e;
(4) Determine the sweep frequency range according to the probe frequency, and observe the impedance phase change in the sweep frequency range in real time;
(5) Save the data for subsequent processing.