Investigation on piezoelectric helix for use as a hydrophone

The piezoelectric helical spring is analyzed for use as a hydrophone. Because the polarity in the helix is arranged parallel to the electrode planes, the shear mode, g/sub 15/ can perform the elastoelectric conversion without any undesired couplings under hydrostatic condition. In this paper, the structural effects are modeled using the concept of stress amplifier. The gain factor, G, is defined as the ratio of the average stress in the piezoceramic to the detected pressure and, therefore, provides a G-fold increase in voltage responsivity. In addition, a solution for increasing the capacitance while maintaining the sensitivity is proposed. Numerical results showing high hydrostatic responsivities are given.