Simulation Study on the Influence of Multifrequency Ultrasound on Transient Cavitation Threshold in Different Media

Abstract

Through the introduction of multifrequency ultrasound technology, remarkable results have been achieved in tissue ablation and other aspects. By using the nonlinear dynamic equation of spherical bubble, the effects of the combination mode of multifrequency ultrasound, the peak negative pressure and its duration, the phase angle difference, and the polytropic index on the transient cavitation threshold in four different media of water, blood, brain, and liver are simulated and analyzed. The simulation results show that under the same frequency difference and initial bubble radius, the transient cavitation threshold of the high-frequency, triple-frequency combination is higher than that of the low-frequency, triple-frequency combination. When the lowest frequency of triple frequencies is the same, the larger the frequency difference, the higher the transient cavitation threshold. When the initial bubble radius is small, the frequency difference has little effect on the transient cavitation threshold of the triple-frequency combination. With the increase of initial bubble radius, the influence of frequency difference on the transient cavitation threshold of the higher frequency combination of triple frequency is more obvious than that of the lower frequency combination of triple frequency. When the duration of peak negative pressure or peak negative pressure of the multifrequency combined ultrasound is longer than that of the single-frequency ultrasound, the transient cavitation threshold of the multifrequency combined ultrasound is lower than that of the single-frequency ultrasound; on the contrary, the transient cavitation threshold of the multifrequency combined ultrasound is higher than that of the single-frequency ultrasound. When the phase angle difference of multifrequency excitation is zero, the corresponding transient cavitation threshold is the lowest, while the change of the polytropic index has almost no effect on the transient cavitation threshold for the multifrequency combination. The research results can provide a reference for multifrequency ultrasound to reduce the transient cavitation threshold, which is of great significance for the practical application of cavitation.

Effects of multi-frequency ultrasonic assisted sodium hypochlorite on the cleaning effect and quality of fresh-cut scallion stems

“…The low frequency US produced cavitation in the liquid faster and with greater force, resulting in a superior cleaning effect. In addition, the use of SF modes and alternating high and low frequencies within the same container space can reduce cavitation thresholds as well as the effects of standing wave effects [43] , [44] . Thus, further experiment was carried out using a US parameter of (20 ± 2) + (28 ± 2) kHz SF.…”

In Vitro Model for the Evaluation of Innovative Transcatheter Debridement Device (TDD): Pericardium-Based Scaffold and Stem Cells to Reproduce Calcificated Valves

“…Another important element for cavitation is represented by the Bjerknes forces, which intensify the fragmentation of the bubbles due to the interaction of the bubbles with each other [ 16 ].…”

“…Furthermore, the non-linear effects, together with the combination of the two frequencies, reduce the threshold to generate cavitation effects. Another important element for cavitation is represented by the Bjerknes forces, which intensify the fragmentation of the bubbles due to the interaction between the bubbles themselves [ 16 ]. The combination of the two frequencies accelerates bubble collapse: cavitation bubbles become more unstable and easier to collapse under the pressure of dual-frequency ultrasound.…”