Micro-Bubble Pressure Measrement Using Ultrasound

Micro-bubbles filled with gas and surrounded by a thin elastic shell are used as contrast agents in medical imaging with ultrasound. The interest in using the micro-bubbles for blood pressure measurements in the left ventricle of the heart and other organs has been raised in the last years. This task requires better understanding of the micro-bubbles properties driven by acoustic force and the conditions for creation of non-linear effects such as appearance of half-harmonic component in the signal radiated from the micro-bubbles. This work uses laboratory experiments in order to investigate the conditions for creation of half-harmonic component. The experiments are designed to better understand the micro-bubble properties and to explore the possible methods for future applications of micro-bubbles for blood pressure measurements. The response of the micro-bubbles to the driving ultrasound force is defined by their physical properties: micro-bubbles resonance frequency , the distribution of the micro-bubbles population radii and gas diffusion process.The micro-bubbles respond in a non-linear manner to the acoustic pressure above specific threshold.