Ferrofluids: Magnets Make It Dance!

Magnetic substances are materials which are attracted to magnets. Iron, steel, cobalt, and nickel are a few magnetic materials. Usually, these substances are thought to be solids. However, what if there were liquid or fluid materials that had the same ability? In fact, there are! The ferrofluids are a group of fluid substances attracted to magnets.

How were ferrofluids made? Ferrofluids were invented by Steve Papell at NASA in 1963. At the time, a ferrofluid needed to be invented to use as a liquid rocket fuel. Using the help of a magnetic field, ferrofluid could be used in space, where the absence of gravity could not allow normal fuel to be used.

Ferrofluids may be classified as colloids. Colloids are fluids containing tiny particles that do not dissolve. In ferrofluids, these particles are nanoparticles as they are at the nanoscale, which means they can be measured in billions of a meter. Furthermore, the particles are made of a magnetic substance known as magnetite. Magnetite is the name of one of the oxides of iron. Magnetite is paramagnetic in nature, because it is only magnetic in the presence of a magnetic field. The fluid in ferrofluids is either an organic fluid or water. Ferrofluids also have a third component known as a surface active agent. Surface active agents prevent particles from dissolving in fluid. Usually, ferrofluids are made of 5% particles, 85% liquid, and 10% surface active agent.

Although NASA uses ferrofluids, it can also be a great DIY project. To make ferrofluid at home, pour some vegetable oil into a bowl, just enough to cover the bottom.

Then add some iron filings and mix well. Your ferrofluid is ready to “attract” some audiences!

Although called ferrofluid, these substances may act like a solid as well as like a liquid. When there is no magnetic field, the ferrofluid acts like a liquid. The particles of magnetite move freely in the fluid. However, as soon as there is a magnetic field, the particles are magnetized. These magnetized particles now form structures within the fluid and make the ferrofluid act like a solid. When the magnet is moved, the magnetite particles return back to their original state, making the ferrofluid act like a fluid once again.

Apart from its use at NASA, ferrofluids are now also used in the medical industry for a technique known as magnetic resonance imaging (MRI). Ferrofluid is also used in computer hard drives and rotating shaft motors in industries. Lastly, ferrofluids may also be used in loudspeakers to soften the vibrations.

Want to watch a ferrofluid in a magnetic field? Watch this video to know more!

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