Pyroelectric properties of moist and dry bone

Electrical polarization has an important influence on various physiological functions of bone. It was investigated using a dynamic pyroelectric method in both moist and dry samples of turkey femur. A special calculation technique was developed to separate the pyroelectric and the thermally modulated conduction currents, based on their different frequency dependencies. An extremely large pyroelectric effect, comparable in magnitude to that of the best ferroelectric materials, could be induced by a small DC bias electric field on moist bone. The polarization and pyroelectric coefficients had very long relaxation times (order of 0.01 s). In the absence of a bias field, the pyroelectric coefficient was induced by an internal field and was spatially nonuniform. The phenomena observed are apparently related to the high orientational mobility and the viscous relaxation characteristics of dipolar water molecules in moist bone. In dry bone, the pyroelectric coefficient was very small, spatially uniform, and independent of bias field.