Highly Isotropic Terfenol-D/PZT Magnetoelectric Sensor Based on Nested Ring Structure

In this paper, we studied a highly isotropic sensor for scalar magnetic field measurements and developed a Terfenol-D/PZT composite magnetoelectric sensor based on a nested ring structure. The effect of applied magnetic field, direction, and bias magnetic field on the output characteristics of the structure was studied, and it was observed that it has good linearity and a wide measurement range. According to a linear theoretical model suitable for small-signal excitation, when the direction of the applied ac magnetic field changes, the ratio of the maximum and minimum output voltages is only 3:1. Both experimental and theoretical results demonstrate that the nested-ring-structured sensor is highly isotropic. It is observed that the isotropy of the magnetoelectric sensor depends not only on the shape isotropy of the piezoelectric and magnetostrictive materials but also on the amplitude of the bias magnetic field.