Heating mechanism of microbubbles and bubble properties

Recently ultrasound and microbubbles are utilized for medical applications such as ultrasound imaging, sonodynamic therapy and so on. In the field of bubble dynamics, it is known that microbubbles can convert the ultrasound energy into acoustic energy or heat energy when they are subjected to an acoustic field. If the heating effect of microbubbles is utilized in a well controlled manner, the HIFU (high intensity focused ultrasound) treatment can be done less invasively and more efficiently. In this paper, the heating mechanism of microbubbles is discussed and analyzed. Next, there are some differences in the desired properties of the microbubble acting as either an echo source or a heat source. The types of gases inside a bubble have a strong effect on the energy emission from the bubbles. It is determined numerically and experimentally that the heat energy from the microbubbles can be changed by changing the gas inside the bubbles.