Department of Bioengineering, Imperial College London, 2 Imperial College Road, South Kensington, London, SW7 2AZ, United Kingdom
JASA Express Lett. 2022 Feb;2(2):022002. doi: 10.1121/10.0009394.
This letter presents the relationship between bubble concentration and the energy ratio of low to high frequency bands of their acoustic emissions. Two sensors, placed perpendicular and concentric to a transmitter, captured the emissions from sonicated microbubbles. Emissions from different bubbles arrived at the perpendicular sensor with small time differences. Low frequencies with periods longer than the time differences interfered constructively, while higher frequencies interfered both constructively and destructively. The low-frequency (2nd-3rd harmonics) to high-frequency (7th-12th harmonics) energy ratio increased with the bubble concentration. The relationship was not observed with the concentric sensor, where the time differences were larger.
这封信介绍了气泡浓度与它们的低频到高频频段能量比之间的关系。两个传感器分别垂直和同心放置在发射器旁边，捕捉到了超声微泡的发射信号。来自不同气泡的发射信号到达垂直传感器的时间差很小。低频信号（2 次和 3 次谐波）的周期长于时间差，因此会产生建设性干扰，而高频信号（7 次到 12 次谐波）则会产生建设性和破坏性干扰。低频（2 次到 3 次谐波）到高频（7 次到 12 次谐波）的能量比随气泡浓度的增加而增加。这种关系在同心传感器中没有观察到，因为同心传感器中的时间差较大。
