Ferrofluids look like pitch-black ink. Developed for the U.S. space program, ferrofluids are made from super small iron particles, only about ten nanometers in diameter and the size of a single molecule. Given a chemical coating, or surfactant, that prevents them from clumping together, the particles are added to oil or water, making a liquid that responds to magnets. Ferrofluids already have been put to work inside loudspeakers, where they help keep the inner parts cool. They also are vital to computer hard drives and semiconductor manufacturing, where they act as seals, keeping out dust and other contaminants. Nanotechnologists want to harness ferrofluids to help operate tiny new sensors or actuators, moving parts that can be controlled electrically. Ferrofluids made with water also could be useful inside the body, as part of tiny pumps or other biomedical devices. In the Laboratory for Electronic and Electromagnetic Systems at Massachusetts Institute of Technology (MIT), electrical engineer Markus Zahn and his research team are exploring ferrofluids potential in nanoscale motors and biomedical devices. All the current uses of ferrofluids involve their responding to permanent magnetic fields, fields that remain constant and don't change over time.

Source: sciencentral.comAdded: 12 June 2006