Piezoelectrical signals generated in air- and water-saturated cancellous bones by an ultrasound wave

Experimental observation of the piezoelectric signals generated in cancellous bone by an ultrasound wave was performed using "piezoelectric cells (PE-cells)". The PE-cell, in which a cancellous bone specimen is used as a piezoelectric element, can correspond to an ultrasound receiver. In this study, two cancellous bone specimens in which the pore spaces were saturated with air and two waters with normal and low conductivities were used. The piezoelectric signals generated in the air- and water-saturated cancellous bone specimens by an ultrasound wave and the ultrasound signals propagated through the specimens were observed. The amplitudes of the piezoelectric signals in the water-saturated cancellous bone specimens were approximately four times of the amplitude in the air-saturated specimen. Both fast and slow waves, which can propagate mainly in the trabecular elements and the pore fluid, respectively, could be observed for the ultrasound signals in the water-saturated cancellous bone specimens, but only the fast wave could be observed for the signal in the air-saturated specimen. From the observed results, it was suggested that the piezoelectric signal generated in cancellous bone by an ultrasound wave could be largely associated with the motion of the pore fluid.