Explore the four most common magnetic field sensors: Hall Effect, AMR, GMR, and SQUID, their workings, and various applications.
Magnetic Field Sensors: A Comprehensive Overview
Magnetic field sensors, or magnetometers, are devices that detect and measure magnetic fields. These tools have a wide range of applications, from navigation and positioning to industrial automation and scientific research. In this article, we’ll examine four of the most common types of magnetic field sensors.
1. Hall Effect Sensors
First on our list is the Hall Effect Sensor. Named after Edwin Hall, who discovered the Hall Effect in 1879, these sensors produce a voltage difference across an electrical conductor, transverse to an electric current in the conductor and a magnetic field perpendicular to the current. These sensors are often used in automotive systems, industrial applications, and consumer electronics because of their durability and cost-effectiveness.
2. Anisotropic Magnetoresistance (AMR) Sensors
Anisotropic Magnetoresistance (AMR) Sensors change their resistance depending on the magnetic field’s direction. AMR sensors, made from thin-film permalloy, are used in various applications, including electronic compasses, position sensing, and vehicle detection.
3. Giant Magnetoresistance (GMR) Sensors
The Giant Magnetoresistance (GMR) Sensor is a quantum mechanical magnetoresistance effect observed in thin-film structures composed of alternating ferromagnetic and non-magnetic layers. The discovery of GMR led to a significant improvement in hard disk drive technology and won the 2007 Nobel Prize in Physics. GMR sensors are used in various applications, including data storage, automotive sensors, and biosensors.
4. Superconducting Quantum Interference Device (SQUID) Sensors
The Superconducting Quantum Interference Device (SQUID) Sensor is the most sensitive of all the magnetic field sensors. SQUIDs work on the principle of quantum interference and are used in medical imaging, geology, and basic research due to their extreme sensitivity.
In conclusion, magnetic field sensors play a vital role in many different sectors, and understanding their differences can help in selecting the right sensor for a specific application.
