title: Enhanced cavitation by using two consecutive ultrasound waves at different frequencies.
abstract: Efficient and noninvasive generation of cavitation bubbles in soft tissue is a challenging task due to the lack of cavitation nuclei (i.e., pre-existing gas bubbles). In this study, we present a method to generate and enhance cavitation activity based on the utilization of two consecutive ultrasound waves at different frequencies. First, a high frequency (5 MHz) high intensity focused ultrasound (HIFU) wave was applied to a tissue-mimicking phantom to induce a rapid temperature rise in the ultrasound focal region. Immediately following the high frequency HIFU wave, a low frequency (1 MHz) HIFU wave was applied to the same focal region to induce acoustic cavitation. We found that cavitation activity was enhanced when the temperature in the tissue-mimicking phantom was first elevated by the high frequency HIFU wave. The enhancement was greater when a higher intensity of high frequency HIFU wave was applied. This result may be due to the temporary super-saturation of air in the initially air-saturated test samples and the reduction of surface tension at an elevated temperature.
authors.affiliation: Department of Mechanical Engineering, The University of Kansas , 1530 W. 15th Street, 5109 Learned Hall, Lawrence, Kansas 66045, USA.
authors.forename: Xinmai
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Mechanical Engineering, The University of Kansas , 1530 W. 15th Street, 5109 Learned Hall, Lawrence, Kansas 66045, USA.
authors.forename: Janggun
authors.initials: J
authors.lastname: Jo