GMR Applications :: science

GMR ApplicationsA Microcontroller-based scheme for placardment of charismatic field position using Giant magnetised Resistor (GMR) in Contactless Measurement and RoboticsOmidreza Esmaeili Motlaghmodule of Electronic Engineering, Mazandaran University ( UMZ ), Babol, IranMagnetic sensors in contactless applicationsMagnetic sensors can be used for all sorts of applications where a contactless measurement of position and orientation is required. For instance in cars, where a large number of sensors are employed, magnetic sensors obviously have great advantages over their counterparts which involve the use of moving parts.Also they are variety of Magnetic sensors used in industry to simplify designs in different cases. For instance the stream measurement using shunt resistor is in some cases visionary or impossible. For large f down(p) rates the shunt resistors are heavy and they cause voltage drop and dissipate heat. They are not insulated and the conductor should be disconnected fo r mounting. Contactless current sensors may be used for remote conductors at high potentials, underground cables etc. Today a wide range of AC and DC contactless current sensors is produced. Also precise contactless magnetic sensors are always required by car industry, chemical industry and more other industries, for measurement of power and many other applications.Solid-state magnetic field sensors are moving into a growing range of new contactless applications because of their small size, low power consumption, and relatively low cost.The first aim of the project therefore will be to become familiar with different kinds of magnetic sensors, especially new GMR family and to investigate their characteristics and behavior in presence of applied magnetic field. 1Giant Magnetic Resistor (GMR)Structure The sensor consists of stack of magnetic and non-magnetic layers and Giant Magnetic Resistivity or GMR set up occur when these ultra-thin magnetic layers are set in close proximity to e ach other. Alternately magnetic and non-magnetic layers can be built up with the magnetic fields either parallel or anti-parallel, creating very sensitive low to high resistance components. The resistance of a GMR sensor as a measure for the applied field varies with the angle between the hard internal magnetization and the soft magnetic covering layers which follows the magnetic field. 2 The Giant Magnetic Resistor is a resistive device whose Ohmic value changes gradually only when a nearer external magnetic field changes its relative orientation and the originated field fanaticism or the distance between magnet and GMR are not relevant within certain limits. Any rotary button or knob containing a magnet on it, may work as a contactless switch when its rotation is detected by a GMR.