| Abstract
| - Dielectrophoresis is an effective method for capturing nanoparticles and assembling them into nanostructures. Thefrequency of the dielectrophoretic alternating current (ac) electric field greatly influences the morphology of resultantnanoparticle assemblies. In this study, frequency regimes associated with specific gold nanoparticle assemblymorphologies were identified. Gold nanoparticles suspended in water were captured by microelectrodes at differentelectric field frequencies onto thin silicon nitride membranes. The resultant assemblies were examined by transmissionelectron microscopy. For this system, the major frequency-dependent influence on morphology appears to arise notfrom the Clausius−Mossotti factor of the dielectrophoretic force itself, but instead from ac electroosmotic fluid flowand the influence of the electrical double layer at the electrode−solution interface. Frequency regimes of technologicalinterest include those forming one-dimensional nanoparticle chains, microwires, combinations of microwires andnanoparticle chains suitable for nanogap electrode formation, and dense three-dimensional assemblies with very highsurface area.
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