Smart multipurpose sensor based on magnetic effects

In this paper a new smart sensor is proposed, based on three different magnetic effects or operational modes, using the same sensor topology, which consists of a magnetic wire as sensing core, two coils as excitation or search means and two electric contacts at the ends of the magnetic wire. The involved magnetic effects are magnetostriction, magneto-impedance and re-entrant flux reversal. Operating the sensor in these three different modes separately and sequentially, one can obtain the response of the sensor related to the three different physical quantities, namely stress, temperature and field. It has been experimentally observed that the total output of the sensor in each one of the three different modes is equal to the product of each corresponding physical quantity function concerned, provided that a given threshold of ambient field and preloaded stress is used to bias the sensing element. Therefore, the three unknown parameters of stress, temperature and field can be determined from a 3×3 matrix equation.