Ferrofluid
Ferrofluid is a novel application of nano technology that was originally developed to control liquid fuel flow in space, and is now used in many commercial applications including computer hard drives, audio speakers, bio-medical procedures and detection of micro-faults in critical steel components (1).
Ferro Fluid is a colloidal suspension of nano scale magnetic particles in a liquid carrier (1). The cores of these particles are made of iron oxides which are known to be compatible with living tissues (2). The particles average about 10nm in size and are coated with a dispersing agent (surfactant) to prevent agglomeration. Normally, the particles are randomly distributed, but in the presence of a magnetic field, each particle aligns along the magnetic force lines so that the fluid behaves as a homogeneous magnetic liquid that responds instantly to changes in the strength and orientation of the magnetic field. (1)
surfactant
A typical ferrofluid may contain by volume 5% magnetic solid, 10% surfactant and 85% carrier. The surfactant must be matched to the carrier type and must overcome the attractive van der Waals and magnetic forces between the particles. (3)
