A Novel MEMS DC Magnetic Sensor Using Thermomagnetic-Piezoelectric Materials with a Coil-Less Reset Approach

摘要

We report a novel MEMS DC magnetic sensor using thermomagnetic-piezoelectric materials with a coil-less magnetization-reset approach. The magnetic sensor consists of a silicon MEMS diaphragm, a piezoelectric PZT thin film, and a thermomagnetic Gadolinium (Gd) sheet. Due to the Gd's thermomagnetic property, the sensor at low temperature (for instant, 9 °C.; below its Curie temperature which is in room temperature range) can sense ambient DC magnetic fields. Without using on-chip coils, the sensor can be easily reset by heating the sensor higher than its Curie temperature (for example, 45°C). According to experimental results, the sensor successfully senses DC magnetic field from 2 to 100 Gauss and is reset at 45 °C. When comparing to conventional NEMS, MEMS, and AMR magnetic sensors (i.e., using magnetic materials requiring on-chip magnetization-reset coils which occupy huge chip footprint), our sensor with the coil-less reset approach can significantly reduce the sensor footprint.