High Sensitivity Giant Magneto-Impedance Micro-Sensor With Grooved Grating Patterned Magnetic Films

The sandwiched laminated soft magnetic films/planar coils Giant Magneto-Impedance sensors exhibit prominent advantages in miniaturization due to compatibility with Micro-Electro-Mechanical Systems. However, the inevitable shape demagnetization leads to the effective permeability of the magnetic films being far less than the nominal permeability of the functional material, which hinders the sensitivity promotion for film-based magnetic sensors. Here, a novel approach is proposed to enhance the effective permeability by introducing micro-grating patterns on the magnetic film surface for developing high-sensitivity magnetic sensorics. The magnetic characterizations of the patterned films demonstrate that the magnetic polarization field generated from the groove wall end faces can significantly compensate for the shape demagnetization. Therefore, a high-sensitivity giant magneto-impedance micro-sensor with grooved grating patterned magnetic films is designed and fabricated by micromachining technology. The experimental results indicate the impedance ratio peaks to 522% at 17.5 MHz, which demonstrates significant potential in developing the sensor array for biosensing and geomagnetic navigation. The strategy, modifying the surface morphology of a film instead of adjusting its compositions, opens a new way to enhance the feature property of a functional material, especially feasible for micro-fabrication.