Relaxor ferroelectric single crystal based hybrid actuator for underwater acoustic noise generation

This report details the development of a microfabricated pump for underwater acoustic noise generation. The goal of MicroHydraulic Transducer (MHT) technology is to provide high power density servohydraulic actilation systems that can be used in a variety of applications. Hydroacoustic actuation is a good application for such technology. The goal here is to develop an acoustic noise source capable of radiating approximately 0.25- 0.5W of acoustic power under water at frequencies ranging from 100-1000Hz. This translates to pressure and flow rate requirements of 15-30kPa and 300- 500ml/s respectively. The MHT relies on the incorporation of discrete piezoelectric elements into a microfabricated device to produce compact high stiffness actuation at high frequencies. These piezoelectric elements used in conjunction with a piezoelectric piston enable the design of a stiff efficient electric to fluidic energy conversion mechanism with a high power density. The device relies on the DRIE fabrication of high-strength silicon membranes to form pistons with membrane tethers. A final device was built and tested and a maximum flow rate and pressure differential of 4ml/min and 350kPa were obtained. It is shown that suitable modifications will enable a future MHT device to match the pressure and flow rate requirements for underwater acoustic noise generation.