Magnetic materials

Most people recognize magnets as toys or materials with limited applicability, such as refrigerator magnets or simple magnets for holding paper when attached to a metal surface. What many people do not know is that in fact magnetic materials (magnets) have a wide range of applications in many areas of our lives, such as medical services, security devices, communications, transportation and even today magnetic materials They are widely used in areas such as jewelry where the development of magnetic bracelets and earrings has changed the way people think about magnetism. Here is a review of the main applications that magnetic materials have in the modern world and the future applicability of the new types of materials that are currently being produced.

compasses

Compasses represent a traditional application of magnets. A compass is an instrument used to measure directions using the earth’s magnetic poles as a reference. The frame of reference consists of the four cardinal points, north, south, east and west. The magnetic compass interacts with the earth’s magnetic field, which is like a giant bar magnet, pointing towards the earth’s magnetic poles.

The Chinese were the first to notice these phenomena despite their lack of knowledge about the electromagnetic forces that cause this effect. The compass was invented during the Han dynasty between the 2nd century B.C. C. and the first century AD. C. and was only used to navigate in the 11th century. It was later introduced to Europe where it was replaced by the dry compass. In the 20th century, the liquid-filled magnetic compass was introduced. The invention of the compass was definitely one of the most important creations in the history of mankind.

Magnetic Resonance Imaging (MRI)

Magnetic resonance is a technique widely used today in medicine for the diagnosis of different diseases such as cancer. Its main use is based on the construction of images of the internal organs of the body avoiding the use of surgery to find and diagnose the disease. Because the body is composed primarily of water molecules, MRI uses the properties of water in the presence of a high magnetic field to produce an anatomical image of specific areas of the body, being especially useful for imaging the brain, muscles and the heart. . In an MRI device, a magnetic field is used to cause hydrogen atoms in water molecules to resonate at a certain frequency, and then a radio frequency pulse is applied that changes the energy state of the spins. When the radio frequency pulse ceases, electromagnetic signals are emitted due to the relaxation of the spins; this is detected by the instrument and an image is formed taking advantage of the tissue contrast.

magnetic nanoparticles

Nanoparticles and nanomaterials consist of materials with sizes less than 100 nanometers. Many types of nanoparticles such as quantum dots, liposomes, gold nanoparticles, carbon nanotubes, and magnetic nanoparticles are designed today for different applications in medicine and industrial processes. Among these materials, magnetic nanomaterials have been widely used for the detection of cancer and many other diseases. Magnetic particles can be used to enhance signals caused by water molecules in the body when a magnetic field is applied as described in MRI, so these nanoparticles serve as contrast agents for MRI. Besides that, they can also be used to kill cancerous tumors by means of hyperthermia. Hyperthermia consists of the production of heat by very small magnetic particles when a magnetic field is applied to them. This heat can be used to kill cancer cells specifically after the accumulation of small particles in a tumor and is being investigated today as an alternative to traditional methods of treating cancer such as radiation therapy.

alarms

Many burglar alarms are based on the use of magnets. Basically, these alarms consist of a contact switch that responds to changes in the environment and sends a signal to a device that makes noise. A permanent magnet is installed in a door or window frame along with a magnetized material in another part of the window or door creating a connection between the two materials once the alarm is activated. When something interrupts the magnetic field created between the magnet and the metal by opening the door or window, the alarm is activated.

Magnetic levitation trains or MAGLEV trains

MAGLEVS trains consist of a mode of transportation based on the use of powerful magnetic fields to suspend, guide and propel trains through the use of magnets instead of mechanical methods such as wheels, axles and bearings. Because these fast vehicles are lifted off the ground by magnetic forces, they are claimed to move faster, smoother, quieter, and require less maintenance than wheeled trains. Acceleration and deceleration can be achieved faster since it is claimed that the system does not depend on friction.

Speakers

Loudspeakers consist of a wire that carries an alternating current. When the wire is in the magnetic field of a circular permanent magnet (which surrounds the wire) it experiences a force that generates sound waves by compression and rarefaction of the air surrounding the device. This vibrates a cone-shaped diaphragm that reproduces the sound generated at the source.

Other uses of magnetic devices include credit and debit cards, televisions, electric guitars, electric motors, and toys, and they represent an important factor in the development of new technologies for different purposes throughout the world.