Integrated Thin Film Magneto-Impedance Sensor Head Using Plating Process

An integrated thin film MI(magneto-impedance) sensor head constructed with a combination of a thin film NiFe MI element and thin film bias and negative feedback coils using a micro-plating technology, has been developed in order to solve the problems of an amorphous wire MI head. The sensor head showed a very high field-detection sensitivity of about 0.41%/A/m(33%/Oe) magnetized with pulse current and a small hysteresis for the change of an external field. We have fabricated a differential type sensor module using a pair of the thin film MI sensor heads. The output voltage of the sensor has a good linearity within the range of [+ or -] 80A/m, and the voltage was 25mV/A/m(2.0V/Oe), and has small thermal drift within 0.1A/m/ [degrees] C. The consumption power of the sensor module was 165mW. Index Terms -- MI, thin film MI sensor head, thin film bias and negative feedback coils, micro-plating technology, differential type sensor module