Novel Magnetic Sensor Using Magnetostrictive-Piezoelectric Thin Film Composite

This proposal addresses the feasibility of fabricating advanced magnetic field sensors based on the properties of a magnetostrictive-piezoelectric thin film composite. By utilizing the giant magnetostriction of Terfenol-D and the very high piezoelectric coupling coefficients of PZT films, it is theoretically possible to achieve very high magnetic field sensitivities. By direct detection of a voltage across a PZT film under strain induced by a magnetic field in a magnetostrictively strained Terfenol-D thin film, estimation of the magnetic field sensitivity, based on a magnetostriction sensitivity greater than 10-710e for Terfenoi-D and a piezoelectric coefficient greater than 10-5/kV-cm-1 for PZT, can approach 10 mV/Oe. Such a device will require simple readout circuitry, and does not require input electrical power. These features offer distinct advantages over competing magnetic sensor technology, including the recently developed GMR sensors. In this program, NZ Applied Technologies offers a novel and economically practical approach for the fabrication of high-quality piezoelectric thin film layers by metalorganic chemical vapor deposition (MOCVD), together with our multiple-target RIF sputtering manufacturing capability for deposition of Terfenol-D thin films. In Phase I of the program the feasibility of a prototype magnetic field sensor made from a Terfenol-D/PZT thin film composite on a silicon membrane or cantilever substrate will be demonstrated.