Soft Magnetic Amorphous Microwires for Stress and Temperature Sensory Applications

Amorphous ferromagnetic materials in the form of microwires are of interest for the development of various sensors. This paper analyzes and argues for the use of microwires of two basic compositions of Co(71)Fe(5)B(11)Si(10)Cr(3) and Fe(3.9(4.9))Co(64.82)B(10.2)Si(12)Cr(9(8))Mo(0.08) as stress/strain and temperature sensors, respectively. The following properties make them suitable for innovative applications: miniature dimensions, small coercivity, low anisotropy and magnetostriction, tunable magnetic structure, magnetic anisotropy, and Curie temperature by annealing. For example, these sensors can be used for testing the internal stress/strain condition of polymer composite materials and controlling the temperature of hypothermia treatments. The sensing operation is based on the two fundamental effects: the generation of higher frequency harmonics of the voltage pulse induced during remagnetization in wires demonstrating magnetic bistability, and magnetoimpedance.