For more than 40 years, the primary application for ferrofluids has been in loudspeakers for cooling, centering of the “voice coil” and smoothing of the sound produced from the electro-mechanical device that drives a speaker. The diagram below shows the speaker cut in half, so you can see where the fluid is applied.
Just a tiny amount of ferrofluid makes a huge difference for the quality of sound and the length of life of over 300 million speakers produced every year! Today the tiny speakers inside your cell phones, laptop computers, tablets and headphones or earbuds may contain ferrofluid – in tiny amounts!
Ferrofluid is also used inside mechanical devices called “vacuum rotary seals” and acts as a seal against moisture, dust and gases. The ferrofluid forms what we call a “liquid O-ring” and is exactly what it sounds like – a ring of fluid that seals a space and protects the moving parts of the device.
These seals are often found in clean rooms and robotic devices that perform functions that require free motion and protection from contamination by the environment outside their working parts. These seals allow us to produce components such as computer chips and memory cards that are flawless.
Ferrofluid for bio-medical applications is usually one of two types:
1) Magnetic Hyperthermia, where particles are injected into a tumor and then excited in a magnetic field to heat the tissue to a point where the tumor cells become weakened and vulnerable.
2) Targeted Drug Delivery, where drugs or antibodies and “targeting molecules” are attached to the nanoparticles and are injected into the blood stream, then guided by magnetic fields to the site of the tumor or lesion.
Both of these methods cause little damage to the body, much less than some current standard therapies.