Chaining and dendrite formation of gold particles

Using the time-averaged dielectrophoretic force from an applied electric field, we have observed the assembly of gold colloid particles into nano/microwires, connections and dendrites according to location within different field regions of a lithographically patterned array of microelectrodes. The frequency of the fields has a marked effect on the structures. In situ inverse microscopy showed hydrodynamic flows, which probably arise from local heating and which play a significant part in shapes formed. Understanding and using the effects will allow the controlled fabrication and positioning of micro- and nanowires or connections at densities far above what is now achievable. (C) 2004 American Institute of Physics.