GMR Sensors

GMR SENSORS

Introduction

A sensor is defined as a device that converts physical, chemical or biological quantities into electrical quantities.

In recent days, many attempts were made to improve the reliability of the sensors and sensor systems and at the same time lower the cost of fabrication. This aims to make the price of the sensor become relatively cheap.

The sensors and sensor systems have been developed for various applications such as motor vehicles, housing (e.g., for security, regulation of air circulation, temperature regulation, setting humidity), delivery of food, or warehouse storage of food (e.g., temperature, humidity, gas concentration).

Magnetic sensors

The resistance of the material depends on the state of magnetization, called the magnetoresistance effect (MR).

Magnetization in the material can be changed by applying an external magnetic field.

Therefore, the material which has a magnetoresistance effect can be used as magnetic field sensor.

GMR is one of the magnetic sensors which can detect magnetic fields of very low nanotesla (nT) range to several hundred millitesla (mT) range. GMR sensors can operate at temperatures above 225°C.

GMR sensor material

Giant magnetoresistance (GMR) material has been developed into various applications of sensor based on magnetic field sensing, such as magnetic field sensor, a current sensor, linear and rotary position sensor, data storage, head recording, and non‒volatile magnetic random‒access memory.

The GMR material has many attractive features, for example, its electric and magnetic properties can be varied in a very wide range, low power consumption, and small size.

Ferrite is one of the material made up of magnetic oxide material that could potentially be used as a constituent layer of GMR.

GMR sensor materials are widely used in Hard Disk Drive (HDD) memory storage devices.