Exploring the limits of dielectrophoretic nanoassembly

DIELECTROPHORETIC (DEP) manipulation has recently gained much attention from nanotechnologists and has been applied for various nanoentity assembly and manipulation, such as forming chains of nanoparticles and nanowires as sensing elements. For example, when a gold colloid suspension is subjected to an ac electric field, "gold pearl chains" will form due to DEP force. In this article, the frequency-dependent DEP manipulation of gold nanoparticles is analyzed using the coreshell sphere model. The simulated relation between electric field frequency and DEP response is found to agree well with the experimental results, where the rate of gold pearl chain formation tended to zero at high- and low-frequency limits and had a maximum within a narrow midrange frequency band. The appropriate control conditions for 2-nm gold particle assembly using DEP are also estimated through the comparisons among DEP, Brownian motion, gravity, and fluid flows induced by electric field. On the other hand, if an optical beam is used to generate the nonuniform electric field and, consequently, the DEP force (i.e., "Optical DEP" or ODEP), to manipulate nanoparticles in static fluidic medium, then drag force and Brownian motion must be considered in understanding the movement of particles. © 2010 IEEE.