Bottom Up Nanostructure Manufacturing
In many situations it is easier to destroy or remove than to create. Building nanostructures is one of these situations as most robust production methods work by etching away unwanted material. This top-down approach is somewhat limiting though as it does not lend itself to making three dimensional structures. Researchers at Duke University’s Pratt School of Engineering however have devised a bottom up method with greater capability.
The researchers put make a liquid solution of the nanoparticles they are working with and a ferrofluid. Ferrofluids are liquids which become magnetized when exposed to an external magnetic field. The strength of the external field determines the magnetic strength of the ferrofluid. When this happens, the particles in the solution move and interact like charged particles. Those with a weaker magnetic field than the ferrofluid act as though they are negatively charged, and those with a stronger field act as though they are positively charged. Thus the researchers can control how the particles attract and repel each other with an external magnetic field.
This should prove very useful as researchers will be able to create new nanostructures not possible before. New kinds of antennas and materials with optical magnetism are two examples.