Ferrofluids are made of colloidal magnetic particles which are suspended in a liquid carrier. The magnetic particles are nano sized (~10nm), and each of the particles are coated with a surfactant to allow them to repel one another.2 It is generally composed of 5% magntic solid, 85% fluid and 10% surfactant.3 Ferrofluids respond to an external magnetic field, which allows the solution to be controlled through the application of the magnetic field.4


Ferrofluids were first discovered in the 1960s at the NASA Research Centre. Scientists were investigating various techniques to control liquids in space. That was when the idea of a magnetic fluid had arisen. They found that the ferrofluids’ location could be changed when a magnetic field was applied. They also found that the strength of the magnetic field could influence the fluidity.5


Ferrofluids were originally discovered for controlling liquids in space. However, as technology evolved, scientists found various ways of including ferrofluids in our everyday life.


Ferrofluids are also used to improve the performance of loudspeakers. When a loudspeaker is used, electrical energy is constantly produced, and is sent through a coil located in the center of a circular permanent magnet. The electric energy along with the magnetic field causes the coil to vibrate, and consequently creating a sound and heat. Covering the coil with ferrofluid, which is then held in place by the circular permanent magnets, inhibits the unwanted resonance and also dispels the heat from the excess energy. This then results with an improved sound quality.6

Medical Treatment

People with affected retina can be prevented from blindess thanks to the use of ferrofluids in medical treatment. If the retina is affected, the individual’s vision will grow weaker and eventually become blind. In the past silicon liquid has been used to heal the retina to its original state. However, it had to be placed at the affected area manually whereas ferrofluid is a much more affective courier for this procedure. Using ferrofluid is much more accurate as there is an external magnet that guides and keeps the fluid at the designated area.7


Some museums use magnetic devices to manipulate the ferrofluid so that it takes the form of creative shapes.

Concept Zero Ferrofluid is a well known American art studio that prides themselves in their unique artwork using ferrofluid.8


The production of ferrofluid is quite an easy task and could be done at home. Some of the most common materials that are used to make ferrofluid are: Ferric Chloride, Ferrous Chloride, Ammonium Hydroxide and Tetramethylammonium Hydroxide (TMAH).

From mixing the iron salts (ferric chloride and ferrous chloride) with the ammonia solution, the nanoparticles of magnetite can be created. The chemical equation for making magnetite is:
Iron(III) Chloride + Iron(II) Chloride + Amonnia + Water -> Iron (II,III) Oxide + Ammonium Chloride
2FeCL3 + FeCl2 + 8NH3 + 4H2O -> Fe3O4 + 8NH4Cl

Then the surfactant (TMAH) is added to coat each nanoparticle with the same electromagnetic charge so that they resist each other. Lastly, the solution is decanted whilst preserving as many magnetic particles as possible.9


There is no data available containing the information about the ecotoxicology of ferrofluids. However, some of the solvents used in its production can be harmful to the environment.

Ferric Chloride solution
Ferric chloride is very harmful to fish and aquatic organisms.10 When Ferric chloride dissolves in water it results in a brown, acidic and corrosive solution. This solution is also used as a clarifying agent in sewage treatment and drinking water production.11

Ferrous Chloride solution
No ecological information available.12

Ammonium Hydroxide
Ammonium hydroxide can be a very ecotoxic substance if not handled with caution. It can cause eutrophication, which is a nutrient pollution of natural waters. This then enhances the growth of some aquatic vegetation and reduces the quality of the water. However, this then creates a disturbance in the local ecosystem as the rapid growth of aquatic plants results in a lack of oxygen in the water, for the marine life.13

Tetramethylammonium Hydroxide (TMAH)
Tetramethylammonium hydroxide is used as the surfactant in ferrofluid. Fortunately its environmental impact is not as severe as the other materials. When TMAH is released into soil and water, it is expected to biodegrade, leach into the groundwater and quickly evaporate.14


Thermal Conductivity The degree to which a substance allows heat to flow through it. Ferrofluid must be able to conduct great amounts of heat as it is generally used for high temperature appplications. E.g. used to remove heat from the coils in the speakers.
Viscosity A measure of how easily a substance flows. The ferrofluid would be a thick liquid since it is filled with magnetite particles. It can be used as a seal to prevent harmful particles from infecting a computer drive, and if it was not high in viscosity the ferrofluid would not be able to hold its position.
Magnetic Sensitive Magnetic sensitivity is a quantitative measure of the extent to which a material may be magnetized in relation to the applied magnetic field. Ferrofluid must be magnetic sensitive as it has magnetite particles flowing within it. The magnetite particles must be magnetic sensitive otherwise it would not be able to change its density accordingly to the strength of the external magnet field.
Heat Capacity The degree to which the amount of heat is required to change the temperature of a substance. Ferrofluid must have a high heat capacity as it is used for high temperature applications.
Density The ratio of mass of a substance to the volume. Ferrofluid can change its density accordingly to the strength of the external magnet. This is why ferrofluid so fascinating.
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