Strain-Modulated Multiferroic Magnetic Field Sensor for Operation up to 500 °C

Magnetic field sensors that can operate at temperatures above 300 °C are necessary for sensing in harsh environments. A strain-modulated sensor composed of AlN and FeCo paired with an AlNiCo magnetic bias circuit and FeCoV flux concentrators capable of operation from 25 to 500 °C is presented. The total package size, including the bias circuit and flux concentrators, is 0.4 cm
³
, and at 500 °C, the noise spectral density of this sensor is 26 nT/√Hz for a 100 Hz signal. At 500 °C, the sensor has a
Q
factor of 1366 and a theoretical bandwidth of 2.5 kHz. The noise spectral density and sensitivity are reported for various temperatures as the temperature is heated from 25 to 500 °C and subsequently cooled from 500 to 25 °C.