Experimental observations of piezoelectric signals generated in cancellous bone at megahertz frequencies

Abstract

Bone can behave as a piezoelectric material, and the piezoelectric effects in bone can be associated with bone formation. However, the piezoelectric properties in cancellous bone with a complicated porous trabecular structure are not sufficiently investigated because a piezoelectric signal is difficult to experimentally observe. In the author’s studies, the piezoelectric signals in air-saturated cancellous bone at 1 MHz have been experimentally observed by “a piezoelectric cell (PE-cell)”, which can correspond to an ultrasound receiver. In this study, the experimental observations of the piezoelectric signals in water-saturated cancellous bone at 1-5 MHz were performed using the PE-cell. The porosity of the bone specimen was approximately 0.65 (65%), and the network of the trabecular elements tended to be oriented in the thickness direction, which matched the ultrasound direction. The burst ultrasound waves at 1-5 MHz were received at the center of the bone specimen in the PE-cell. The output electrical signals in the PE-cell were observed. The signal amplitudes in water-saturated bone did not significantly vary with frequency, except for a larger amplitude at 2 MHz. The signal amplitudes in water-saturated bone were larger than those in air-saturated bone, and their ratios were found to vary from 6 to 32.