High sensitive and heat-resistant magnetic sensor using magnetostrictive/Piezoelectric Laminate composite

A highly sensitive and heat-resistant magnetic sensor using a magnetostrictive/piezoelectric laminate composite is investigated. The sensing principle is based on the magnetostrictive and piezoelectric effect, whereby a detected yoke displacement is transduced into a voltage on the piezoelectric materials. The sensor is intended to detect the displacement of a ferromagnetic object in a high temperature environment, where conventional magnetic sensors are not available. Such applications include sensors in automobile engines and machinery used in material processing. The sensor features combination of a laminate composite of magnetostrictive/piezoelectric materials with high Curie temperatures and an appropriate magnetic circuit to convert mechanical displacement to sensor voltages. This paper describes the sensing principle and demonstrates experimental results using a composite of Terfenol-D and Lithium Niobate to assure high sensitivity of 50 V/mm and a temperature operating range over 200/spl deg/C.