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

     Sensitive and fast-response micro-sensors are evaluated now as leading advanced elements for innovative measurement and control systems in creation of new industries. The revolutionary technology of magnetic sensors based on the effect of giant magnetic impedance (GMI) has all chances to overtake the existing sensors, both in performances and in attractive prices. GMI sensors feature the high sensitivity, micro sizes, fast response, and low energy consumption, which is making them unique in comparison with other magnetic sensors, like magneto-resistive sensors, Hall sensors and induction sensors.

     GMI sensitivity in amorphous microwires in an order higher than in materials with giant magneto-resistivity.

     Recently, the demands are growing for sensitive micro-magnetic sensors for technological improvements in automation, mechanization, computerization and biotechnology using high-quality measurement and monitoring systems.

     Below, different types of sensors are compared:

Sensor type

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 that 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.
  • The proprietary CMOS FET IC of the sensor, invented in 1997, uses the unique response of the MI effect on pulsed current.
  • positive or negative feedback in the electronic circuitry of the sensor provides for either high resolution linear sensors or sustainable switchable sensors.