Effect of Pore Fluid on Piezoelectric Signal in Cancellous Bone Generated by Ultrasound Irradiation

Piezoelectric signals at 1 MHz generated in bovine cancellous bone by ultrasound waves were experimentally and numerically observe to investigate the effect of the pore fluid. The experimental observation was executed using a “piezoelectric cell (PE-cell)” which is an ultrasound receiver adopting a cancellous bone specimen as the piezoelectric element. The numerical observation was executed using a piezoelectric finite-difference time-domain (PE-FDTD) method, which is an elastic FDTD method with piezoelectric constitutive equations. The X-ray microcomputed tomographic image of the cancellous bone specimen was used to reconstruct the bone model. The experimental results showed that the piezoelectric signal amplitude in the water-saturated cancellous bone was leger than the amplitude in the air-saturated bone. When the piezoelectric signal was assumed to be not generated from the interface between the trabecular element and the pore fluid, the numerical results showed that the piezoelectric signal amplitude in the water-saturated cancellous bone was larger, which was similar to the experimental results.