The discovery of the effect of giant magnetic impedance in wires (GMI effect) made big changes in production of magnetic sensors, operating in nano-Tesla range.

     Sensitive and low-inertial micro-sensors, now estimated as leading advanced elements for advanced measurements and management systems to create a new industry. Relatively new technology of magnetic sensors based on the effect of giant magnetic impedance (GMI) has a chance to overtake, exiting sensors technology, on characteristics and a small price. GMI sensors have the following characteristics as big sensitivity, micro-sizes, low inertia, and low energy consumption, what’s make them unique if we compare with other magnetic sensors, like magnetoresistive sensors, Hall sensors and induction sensors.

     GMI sensibility in amorphous microwires in one order greater than sensibility in materials with giant magnetoresistivity.

     Recent years starts to grow demands for sensitive micro-magnetic sensors for technological improvement in automation, mechanization, computerization and biotechnology using high-quality measurement and monitoring systems.

     Below are different types of sensors:

Sensor

Size

Resolution

Speed response

Consumption

Hall sensor

10~100 μm

0,5 Oe /± 1 kOe

1 MHz

10 mW

MR sensor

10~100 μm

0,1 Oe /± 100 Oe

1 MHz

10 mW

GMR sensor

10~100 μm

0,01 Oe /± 20 Oe

1 MHz

10 mW

Induction

10~20 mm

1 μOe /± 3 Oe

5 kHz

1 W

MI sensor

1~2 mm

1 μOe /± 3 Oe

1 MHz

10 mW

SI sensor

1~2 mm

0,1 Gal /± 30 Gal

10 kHz

5 mW

 

     MI sensor is a new magnetic sensor includes four key technologies:

  • amorphous wire (λ = -10-7) with diameter 15 – 30 microns.
  • effect of magnetic impedance discovered in 1993 year based on magnetoinductive effect.
  • scheme of CMOS FET sensor uses the answer of MI effect on pulsed current, discovered in 1997 year.
  • positive and negative feedback loop in electric scheme of sensor, for high resolution linear sensors and sustainable switchable sensors,