Evidence for different sources of stress-generated potentials in wet and dry bone.

Physiologically moist bone and dry bone behave differently when tested for electrical response to cantilever bending. To characterize this difference more precisely, voltages were generated in the same specimen in each of the two states via the same testing procedure--changing the electrode-to-force distance by moving the electrodes and holding the force position constant. In the dry state, a non-systematic pattern of voltages versus electrode position was generated. In the wet state, a linear relationship was found. Furthermore, the sign of the concave positive regions reversed to concave negative on wetting the specimen. The implication is that different electromechanical transduction mechanisms are involved in the wet and dry cases. The dominant mechanism in the wet case is taken to be the streaming potential rather than piezoelectricity.