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We describe an assembly technique useful for generating ordered arrays of nanowires (NWs) between electrodes via dielectrophoresis (DEP) and an analysis technique useful for extracting quantitative information about the local electric fields and dielectrophoretic forces from video microscopy data. By tuning the magnitude of the applied electric fields such that the attractive forces on the NWs are of the same order of magnitude as the Brownian forces, and by taking advantage of the inter-NW repulsive forces during DEP, NWs can be assembled into parallel arrays with high reproducibility. By employing a particle-tracking code and analysis of NW motion, we demonstrate a method for quantitative mapping of the dielectrophoretic torques and NW-surface interactions as a function of position on the substrate, which allows a more complete understanding of the dynamics of the assembly and the ability to control these parameters for precise assembly.

The construction of three-dimensional (3D) objects, with any desired surface patterns, is both critical to and easily achieved in macroscale science and engineering. However, on the nanoscale, 3D fabrication is limited to particles with only very limited surface patterning. Here, we demonstrate a self-assembly strategy that harnesses the strengths of well-established 2D nanoscale patterning techniques and additionally enables the construction of stable 3D polyhedral nanoparticles. As a proof of the concept, we self-assembled cubic particles with sizes as small as 100 nm and with specific and lithographically defined surface patterns.