The term Ferrofluid describes a fluid that has the properties of a liquid and is composed of tiny magnetic particles and hence is strongly magnetized by a magnetic field. Ferrofluids were discovered in the 1960s by scientists at the NASA Research Center. The scientists were trying to find possible methods of handling and controlling liquids in space. Ferrofluids are easy to handle because the fluid location can be controlled through the use of a magnetic field. They can be forced to flow by varying the strength of the magnetic field.
Ferrofluids are prepared by suspending tiny particles (10 nm diameter) of magnetic solids in a liquid medium. The liquid medium fluid can be water or an organic solvent. When a magnetic field is applied to a ferrofluid, the entire liquid pulls towards the magnetic field by the nanoparticles attracted to the field.
Researchers mostly use ferrofluids prepared from small particles of magnetite (Fe3O4). Tiny particles of ferromagnetic metals like cobalt and iron are also used to prepare Ferrofluids. They also use magnetic compounds, like manganese zinc ferrite (ZnxMn1-xFe2O4). Other common minerals for making these magnetic particles include iron oxides like hematite (Fe2O3). Usually, a hydrocarbon is used to coat the surface of each of the metallic particles to prevent clumping of the nanoparticles on each other.
Ferrofluids have found a wide variety of uses. They have exciting real-world applications because of their property to flow through forced positioning by the strength of the magnetic field. Another feature that influences their application is the capability to absorb electromagnetic energy at convenient frequencies and heat up. The solvent in ferrofluids also can be applicable for their ability to reduce friction; this makes them useful in transportation applications and in electronics.
1. Rotating Shafts
Ferrofluids are used mechanically in rotating shaft seals. These rotating shaft seals used in vacuum chambers and rotating anode X-ray generators. A Ferrofluid held in place by magnets is used as a liquid O-ring through which a rotating shaft enters a chamber of either low or high-pressure. The Ferrofluid is used to form a tight seal, and also to eliminate most of the friction.
Ferrofluid seals are also used to remove dust particles in high-speed computer disk drives. They prevent dust and other impurities from the drives hence protecting the data-reading heads from crashing into the disks.
Ferrofluids are used to improve the performance of speakers and improve sound quality. In a speaker, a coil at the center of the circular magnet is used to carry the electric energy. Due to the magnetic field caused by electrical power, the coil vibrates and produces sound and heat. The electric loop is run through a Ferrofluid, controlled by the circular permanent magnets. The Ferrofluid dampens the unwanted resonances of the music and helps dissipate the heat from any excess energy to the coil.
5. Hydraulic suspension pistons use ferrofluids.
By varying the strength of the magnetic field, it allows the suspension to be hard or soft according to what is required of the piston.
6. Mechanical engineering,
Ferrofluids work like a lubricant for magnets because of their chemical composition. When you apply them to the surface of a neodymium magnet, the magnet can smoothly move along a surface.
7. Ferrofluids have mechanical and aerospace applications. For instance, they can be used in dampers. They are popular in helicopters that operate with many different vibrations.
8. Ferrofluids are applied in heat dissipation.
This is using the Ferrofluid as a heat conductor. If equipment heats up when functioning, to extract the heat and keep it not too hot, a ferrofluid can be used to connect it to another machine of much bigger heat capacity. The Ferrofluid can alternatively be used to dissipate heat to a much bigger open surface. In this case, a Ferrofluid is used as an excellent conductor in a solid conductor that affects the equipment’s operation, (example through vibration).
Experiments in the biomedical area of research are in progress to validate the applications of Ferrofluids in the field. Research is being conducted to design ferrofluids that can be used to carry medications to specific locations in the body. They could also be useful in directing drugs to certain parts of the body. It is possible to use applied magnetic fields. This could be helpful in treating cancerous cells and tumors directly with chemotherapy without wrecking other uninfected parts of the body.
10. Contrast agents for the MRI scans
Investigations are ongoing to enable the use of ferrofluids as contrast agents for the MRI scans (Magnetic Resonance Imaging). Research suggests that Ferrofluids will possibly be used to create an artificial heart with no mechanical parts. The heart will be surrounded by magnets, and the Ferrofluid fixed to the frame of the heart. The heart will then expand and contract, to imitate the pumping of a real heart when needed. Researchers have already been able to develop an artificial heart that uses ferrofluids and electromagnets instead of mechanical parts or motors.
11. Body armor
The development of a new body armor using Ferrofluids is in process. The armor utilizes Ferrofluid in hollow fibers, and it could act as a plastic splint in battle. By spinning the fabrics out of Ferrofluid in the fibers, clothing that can stiffen when exposed to a magnetic field can be made. They are used during combat, or out in the area in case of an injury. The clothing material will stiffen to protect broken limbs by creating a brace.
12. Ferrofluid could be verified by medical researches to be used to cure retinal detachment by sealing tiny retinal holes. Retinal detachment is the leading cause of blindness,
13. In optics, researchers are confident they will be able to create high-quality reflective surfaces inside telescopes by suspending Ferrofluid in ethylene glycol. This will improve the observation of astronomical bodies.
Many magnetic fluids can be classified as ferrofluids because they are colloidal suspensions of fine magnetic particles. Magnetic fluids with suspensions of larger magnetic particles are not ferrofluids and are usually non-stable. The stability of a ferrofluid is considered in terms of various forces and torques on the suspended magnetic particles. Ferrofluids have full technological applications, and there is a promise of many uses in medicine like hyperthermia, cell separation, and drug targeting.