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Ferrofluids

December 23, 2013

Have you heard of ferrofluids? These magical substances not only lend themselves to gorgeous art, but they also have plenty of functional applications. Science and art unite – it’s the best of both worlds!

The term ferrofluid refers to ferromagnetic nanoparticles suspended in a carrier fluid typically made of an aqueous or organic solvent. LOL WUT?! It means teeny pieces of iron-containing metal suspended in liquid, like water or kerosene. One nanometer = 0.0000001 cm, meaning they’re so small that Brownian motion prevents them from settling out of solution. A ferrofluid also makes use of surfactant to prevent the nanoparticles from clumping up, allowing the metal in solid phase to coexist with the carrier in liquid phase. The sciencey way to say this is “colloidal liquid.”

The cool part comes in when you place the ferrofluid into a magnetic field. The tiny particles feel the magnetic force and adopt the most energetically stable conformation by following the magnetic field lines. As the magnetic force and the force of gravity balance out, the end result is a series of shiny liquid spikes.

Ferrofluids are so metal (literally and figuratively)

So by applying a magnetic field to the fluid you get some badass liquid sculptures. But – SPOILER ALERT – there’s more. Magnetic fields are created by electric current, and that current can be changed. When you apply a dynamic field to the ferrofluid you create an amazing living sculpture. Feast your eyes:

So how is this magical substance used in real life applications? Well, ferrofluids can be used in computer hard drives to form magnetic seals between the spinning disc and the stationary wall. They’re also used to control overheating in loudspeakers by essentially “soaking up” heat from electronic components. The fluid becomes less magnetic as it’s temperature rises, so placing a magnet near the heated coil allows the colder, more magnetic particles to circulate toward the heat source. The end result is an efficient circulation of particles that transfer excess heat away from the speaker so you can bump your Miley at maximum volume without fear.

Ferrofluids surround the voice coil, doing science and shit so your speakers don’t overheat.

There’s also loads of hopeful medical applications for ferrofluids that are still in development, specifically in regards to cancer treatment. Scientists hope to bind chemotherapy drugs directly to the magnetic nanoparticles which they could then inject into a patient. They could then use a strong magnet at the tumor site to accumulate drug locally (preventing loads of unwanted toxic side effects of systemic drug administration).

In the same vein (har har) the injected ferrofluid could be used to thermally ablate a tumor. Because magnets are polarized (they have a positive and negative pole), the magnetic nanoparticles will align with the direction of the applied field. Oscillating this field 180˚ would cause these particles to vibrate very rapidly, generating a large amount of heat. This phenomenon is called magnetic hyperthermia. If done carefully, it might allow doctors to essentially “burn away” tumor tissues from the inside out – possibly lessening the need for surgery.

So ferrofluids make insanely gorgeous living sculptures, keep our electronics and music systems running smoothly, and could potentially help treat cancer someday.

Ferrofluids. Got. Swag.

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From → Physics

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