Ferrofluids

FERROFLUIDS

By Varun Bisht

JANUARY 2017

Born amongst the chaos of the space race of the 1900’s, ferrofluids, the brainchild of NASA’s scientist Steve Pappel, have mesmerised scientists and artists alike for generations with their queer interactions with magnetic fields.

A ferromagnetic fluid, as the name suggests, is a fluid medium (mostly water or oil) containing nano-sized magnetic particles in small amounts (5% by volume). Their ability to gracefully float about the liquid in brownian motion is due to none other than their surfactant coating.  This special soap like compound, using a repulsive electrostatic force, prevents these magnetic particles from being attracted to each other, in a process known as magnetic clumping.

But what could possibly explain the unique shapes these fluids take up in the presence of a magnet? When a magnetic field is brought near a ferrofluid, every particle aligns itself individually in accordance to the strength with which the magnetic field attracts it, resulting in the sharp peaks and troughs of the jagged structures that ferrofluids are known to form. This process is called normal field instability, and every ferrofluid owes its signature spiky appearance to it.

But, surprising as it is, ferrofluids have a higher purpose than keeping you from boredom. Their magnetic properties were originally meant to be incorporated in rocket fuel. By incorporating magnetic particles into the fuel, it could be easily driven into its engines using nothing but magnets in places where gravity is unable to aid in this process, such as space, thus leading to a sharp drop in energy consumption, and saving our earths depleting natural resources.


A ferrofluid on a plane glass surface

Though the idea was abandoned as it increased the crudity of the fuel, ferrofluids have still found their way into our daily life, and are now used extensively in electronic devices such as loudspeakers, where they are used to remove the heat from the voice coil,  and are even used to seal hard drives, as they prevent the entry of any unwanted dust particles.  Besides this, they are used to make magnetic ink for bar codes and have also found a place in the medical field,  where they are extensively used in brain surgery.

Over the last 50 years of their invention, ferrohydronamics, as their study is called, has provided a new perspective to any problem faced by mankind. For all we know, the very gears in your clock might go obsolete, as watchmakers can now simply use magnets to realign ferrofluid with every passing minute to tell the time. PC cooling fans would become extinct, revolutionising the way future innovators design laptops in the years to come.

It is due to the painstaking work of Steve Pappel, that 50 years ago a new door was opened, beyond which lies the power and the ability for us to change the world.

*Brownian motion is the random movement of the particles of a fluid due to the presence of other molecules of the fluid around them.