Modelling the dynamics of microbubble undergoing stable and inertial cavitation: delineating the effects of ultrasound and microbubble parameters on sonothrombolysis

• Main Authors: Tan, Zhi Qi, Ooi, Ean Hin, Chiew, Yeong Shiong, Foo, Ji Jinn, Ng, Yin Kwee, Ooi, Ean Tat
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Article
• Language: English
• Published: 2024
• Subjects: Engineering; Acoustic waves; Cavitation
• Online Access: https://hdl.handle.net/10356/180064
• Institution: Nanyang Technological University

Sonothrombolysis induces clot breakdown using ultrasound waves to excite microbubbles. Despite the great potential, selecting optimal ultrasound (frequency and pressure) and microbubble (radius) parameters remains a challenge. To address this, a computational model was developed to investigate the bubble behaviour during sonothrombolysis. The blood and clot were assumed to be non-Newtonian and porous, respectively. The effects of ultrasound and microbubble parameters on flow-induced shear stress on the clot surface during stable and inertial cavitation were investigated. It was found that microbubble translation towards the clot and the shear stress on the clot surface during stable cavitation were significant when the bubble was about to undergo inertial cavitation. While insonation of large microbubble (radius of 1.65μm) at low frequency (0.50 MHz) produced the highest shear stress during stable cavitation, selection of these parameters is not as intuitive for inertial cavitation due to the strong competing effect between jet velocity and translational distance. An increase in jet velocity is always accompanied by a decrease in the translational distance and vice versa. Therefore, a right balance between the jet velocity and the translational distance is critical to maximise the shear stress on the clot surface. A jet velocity of 303 m/s and a distance travelled of 5.12μm at an initial bubble-clot separation of 10μm produced the greatest clot surface shear stress. This is achievable by insonating a 0.55μm microbubble using 0.50 MHz and 600 kPa ultrasound.