Ferrofluid is a liquid that becomes strongly magnetized in the presence of a magnetic field. It is composed of nanoscale ferromagnetic or ferrimagnetic particles suspended in a carrier fluid using a surfactant. When magnetized, the fluid forms peaks and troughs due to the competition between magnetic and other surface energies. Ferrofluid was first created by NASA in 1963 for use as rocket fuel and has since found applications in speakers, hydraulic systems, biomedical research, and potential future uses like artificial hearts and body armor.

2. • WHAT IS THE FERROFLUID?..............................................................:1
• HISTORY OF THE COMPOUND.................................................:2
• HOW DOES THE CORROGATIONS OCCUR? …....................:3
• CHEMICAL STRUCTURE OF THE FERROFLIUD …...................:4
• USEFUL PROPERTIES OF FERROFLUID......................................:5
• APPLICATIONS OF FERROFLUID............................................:6

3. • A FERROFLUID IS A LIQUID WHICH BECOMES HIGHLY
MAGNETIZED IN THE PRESENCE OF A MAGNETIC
FIELD.
• THE DISTINCTIVE ‘SPIKEY’ SHAPE OF A MAGNETIZED
FERROFLUID IS CAUSED BY THE NEED TO FIND THE
MOST STABLE SHAPE IN ORDER TO MINIMIZE THE
TOTAL ENERGY OF THE SYSTEM, AN EFFECT KNOWN AS
THE NORMAL-FIELD INSTABILITY. THE FLUID IS MORE
EASILY MAGNETIZED THAN THE SURROUNDING AIR, SO
IS DRAWN OUT ALONG THE MAGNETIC FIELD LINES,
RESULTING IN THE FORMATION OF PEAKS AND
TROUGHS. HOWEVER, THE EXTENSION OF THE
FERROFLUID IS RESISTED BY GRAVITY AND SURFACE
TENSION.

4. • IN 1963, STEVE PAPELL OF NASA CREATED
FERROFLUID FOR USE AS ROCKET FUEL. HIS TEAM OF
NASA SCIENTISTS WERE INVESTIGATING METHODS OF
DIRECTING FLUIDS IN SPACE AND REALIZED THAT
MAGNETIC FLUIDS COULD BE COMPLETELY
CONTROLLED BY THE APPLICATION AND VARIATION OF
A MAGNETIC FIELD.
• THE SOLUTION OFFERED BY NASA'S
SCIENTISTS WAS A NEW CLASS OF
MATERIALS "FERROFLUIDS".
• THE FIRST CONFIRMED APPLICATION OF
FERROFLUIDS WAS DURING THE APOLLO
MOON LANDING PROJECTS.

5. • THE FORMATION OF THE CORRUGATIONS LOWERS THE
MAGNETIC ENERGY OF THE SYSTEM BUT RAISES THE
GRAVITATIONAL ENERGY AND SURFACE FREE ENERGY.
• THIS OCCURS BECAUSE THE FLUID IS COMPOSED OF TINY
MAGNETIC PARTICLES, UP TO 100 TIMES SMALLER THAN
THE WAVELENGTH OF VISIBLE LIGHT.
• WHEN THESE FORCES ARE BALANCED, THE MINIMUM
ENERGY CONFIGURATION IS ACHIEVED. BECAUSE
FERROFLUIDS ARE VERY EASILY MAGNETIZED (THEY HAVE
AN INCREDIBLY HIGH MAGNETIC SUSCEPTIBILITY), THE
PEAKS CAN BE PRODUCED USING A SMALL BAR MAGNET.

6. • THE PARTICLES IN A FERROFLUID HAVE A DIAMETER
OF 10 NANOMETERS OR LESS AND ARE COMPOSED
OF A FERROMAGNETIC, HIGHLY MAGNETICALLY
SUSCEPTIBLE COMPOUND SUCH AS MAGNETITE
(FE 3O4) OR HEMATITE (FE 2O3).
• THE PARTICLE SIZE HAS TO BE SMALL ENOUGH TO
ALLOW THEM TO BE EVENLY DISPERSED THROUGH THE
LIQUID BY BROWNIAN MOTION (THE RANDOM
MOTION OF PARTICLES IN A LIQUID DUE TO
COLLISIONS WHICH OTHER MOLECULES) BUT LARGE
ENOUGH FOR THEM TO EACH MAKE A SIGNIFICANT
CONTRIBUTION TO THE MAGNETIC RESPONSE OF THE
FLUID.

7. • THE SURFACTANT'S VAN DER WAALS FORCES STOP THE
MAGNETIC NANOPARTICLES AGGREGATING IN THE
SOLUTION. DIFFERENT SURFACTANTS WORK IN DIFFERENT
WAYS BUT THE GENERAL PRINCIPLE IS THAT THE
SURFACTANT CREATES A LAYER AROUND THE PARTICLE
WHICH WILL REPEL OTHER COATED NANOPARTICLES.
• THE SURFACTANT IONS FORM A LAYER OF CHARGE AROUND
THE NANOPARTICLE, REPELLING OTHER CHARGED,
SURFACTANT COATED PARTICL
• THE ADDITION OF A SURFACTANT IS CRUCIAL, IT HAS THE
NEGATIVE EFFECT OF DECREASING THE VISCOSITY OF THE
FLUID IN THE MAGNETIZED STATE AND MAKING IT
‘SOFTER’. AS MOST APPLICATIONS REQUIRE A ‘HARD’ FLUID
IN THE MAGNETIZED FORM, THIS IS AN IMPORTANT FACTOR
TO CONSIDER WHEN CHOOSING THE FERROFLUID
COMPOSITION.

8. 5. USEFUL PROPERTIES OF FERROFLUID
• MAJOR BENEFIT OF FERROFLUID IS THAT THE LIQUID
CAN BE FORCED TO FLOW VIA THE POSITIONING AND
STRENGTH OF THE MAGNETIC FIELD AND SO THE
FERROFLUID CAN BE POSITIONED VERY EXACTLY.
• FERROFLUIDS ALSO HAVE THE CAPABILITY OF REDUCING
FRICTION, MAKING THEM USEFUL IN A VARIETY OF
ELECTRONIC AND TRANSPORTATION APPLICATIONS.
• FERROFLUIDS CAN HAVE VERY HIGH THERMAL
CONDUCTIVITIES AND THEIR HEAT TRANSFER PROPERTIES
ARE EXPLOITED IN DEVICES SUCH AS LOUD SPEAKERS
WHERE THEY ARE USED TO COOL THE VOICE COIL.
• FERROFLUIDS LOSE THEIR MAGNETISM AS THEY ARE
HEATED, FULLY LOSING THEIR MAGNETIC PROPERTIES
WHEN HEATED TO A HIGH ENOUGH TEMPERATURE,
KNOWN AS THE CURIE TEMPERATURE.

9. • FERROFLUIDS ARE ALSO THE FOCUS OF CURRENT
SCIENTIFIC RESEARCH AND HAVE THE POTENTIAL TO
BE USED IN MANY MEDICAL APPLICATIONS. IN
MAGNETIC DRUG TARGETING FOR EXAMPLE, WHERE
DRUGS COULD BE ENCLOSED BY FERROFLUID AND,
ONCE INJECTED INTO THE SPECIFIC BODY AREA
REQUIRING TREATMENT, A MAGNETIC FIELD COULD BE
APPLIED TO KEEP THE DRUGS IN THIS TARGET AREA.
THE LOCALIZATION WOULD LIMIT EXPOSURE TO THE
REST OF THE BODY AND ENABLE THE DOSAGE LEVEL
TO BE DECREASED, REDUCING THE ADVERSE SIDE
EFFECTS EXPERIENCED BY THE PATIENT.

10. /HYDRAULIC SUSPENSION PISTON
S
• FERROFLUIDS CAN BE USED IN HYDRAULIC
SUSPENSION PISTONS, WITH THE STRENGTH OF THE
MAGNETIC FIELD ALLOWING THE SUSPENSION TO BE
HARD OR SOFT DEPENDING ON WHAT IS NECESSARY.

11. /BODY
ARMOUR
• FERROFLUIDS COULD BE USED TO KEEP US SAFE
TOO: NEW BODY ARMOUR IS BEING DEVELOPED BY
MIT WHICH UTILISES FERROFLUID IN HOLLOW
FIBRES. THIS BODY ARMOUR COULD ACT AS A
ARTIFICIAL SPLINT IN THE HEAT OF BATTLE.

12. /USE AS A
CONTRASTING AGENT FOR MRI SCANS
• CURRENTLY, RESEARCH ON USING FERROFLUIDS TO
CREATE AN ARTIFICIAL HEART WITH NO MECHANICAL
PARTS IS BEING UNDERTAKEN BY SUPROCK
TECHNOLOGIES. BY SURROUNDING THE HEART WITH
MAGNETS, THE FERROFLUID FIXED TO FRAME OF THE
HEART WILL EXPAND AND CONTRACT WHEN NEEDED,
IMITATING THE PUMPING OF THE REAL THING. IF
DEVELOPED CORRECTLY THIS SYSTEM MAY BE A
BETTER OPTION THAN CURRENT HEART ASSIST
DEVICES BECAUSE THEY DO NOT HAVE MOVING
PARTS, MEANING THERE WILL BE LESS STRESS ON THE
HEART AND THEY WILL ALSO BE CHEAPER.

13. • FURTHER DISPARATE FIELDS IN WHICH FERROFLUIDS
CAN BE USED ARE:
• HEAT TRANSFER
• ANALYTICAL INSTRUMENTATION
• ART
• AEROSPACE