A combinational method of laser and hydrophone measurements in ultrasound propagation for evaluating elasticity of regenerating cartilage sample

It is useful for maturity evaluation of regenerating cartilage to measure the temporal change of its stiffness. In this study, a laser and hydrophone-based measurement of ultrasound vibration applied to the measuring object (sample) is investigated for evaluating the stiffness of thin regenerating cartilage sample. Surface particle velocity and acoustic pressure of the sample when applying sinusoidal ultrasound to the sample are measured by a laser Doppler vibrometer and a hydrophone, respectively. Then the acoustic impedance is evaluated by using the measured particle velocity and acoustic pressure. The feasibility of this method was investigated by conducting fundamental experiments using agar-based homogeneous phantoms. Moreover, this method was also applied to in vitro measurements using auricular cartilage samples regenerated in beagles.