*4.3. Magnetoresistor Sensor*

It is well-known that electrical conductivity of MREs can be affected by the intensity of the applied magnetic field allowing them to be used in various applications [94]. However, MRE is not categorized as electric conductors. MRE is capable of operating as active devices of the electric circuit that allows to control output voltage in magnetic field by addition of iron and graphite microparticles. Therefore, one of the applications of MRE could be a magnetoresistor sensor device. Bica [147] reported that MRE is applicable for quadrupolar magnetoresistor and active element of electric circuit. The preparation of electroconductive MRE was conducted by polymerization of SR with addition of silicone oil, CI microparticles, graphite powder, and catalyst. The electrical conductivity of MRE was found to be affected by magnetic field intensity. Thereby, the voltage at the output terminals of the MR sensor device is considerably influenced by the intensity of the transverse magnetic field, for control voltages kept constant. Hence, electrical conductivity is influenced by magnetic field intensity, applied voltage and time [148].
